Hey DDB, I love your site. I browse the forums every day, I actively encourage my players to use your tools for character building, and own an absolute crapton of content on this website. I've been actively using DDB for about a year now, and I've been a subscriber for about half of that time, when I started DMing games. Again, the website is great, but there are many many  things that need adding or improving. Some, if not most, of these things are features that people have been asking for, some might be new ideas, so I apologize in advance for beating some dead horses, but I just wanted this list to be as complete as possible. I've decided to divide it all into three sections: Things a player wants/needs, things a DM wants/needs, things a website user wants/needs. So, without further ado:

Features for players

• Character options are a mess. In the character builder, races are all arranged alphabetically, in groups, or by race with subraces. It's ridiculously inconsistent. While this is a result of the physical books being sorted this way, I don't think that this should matter. The different kinds of Elves not being Elf subraces anymore doesn't make them less Elven. Why are they not grouped when Lineages are? Why aren't the Genasi grouped anymore? If you insist on not grouping them (which you seem to, looking at other responses in threads), at least name them in a way that makes them not autosort all over the place. ("Genasi, Water", instead of "Water Genasi" would for example not have it sort by W)
• Homebrew is not obvious. If I have a subscriber DM that has some homebrew subclasses in their collection, it is impossible for me to tell in the character creator which subclasses are HB and which are not. This should be clearly marked: The MTG subclasses have tags for them, like the Spores Druid. Why does homebrew not have that? This goes for items in the Character Sheet as well. Players that have been playing for a while will know which ones are official and which are not, but newer players won't.
• We need toggles for status conditions, Rage, Bladesong, Wild Shape, Symbiotic Entity, etc.. I don't know about others, but I constantly forget that my speed increases when I'm Bladesinging and I keep forgetting about Rage Damage.
• Having to mark a Custom Action to Display As Action separately makes no sense. Why would I create a custom action to then not have it appear on my sheet?
• Spells with 1A, 1BA and 1R should display in their Actions page by default. I shouldn't have to mark them as Actions for them to appear there.
• Optional Rules toggle. There are many many optional rules that I should be able to toggle on and off on character sheets. Spell Points are one that many people have been requesting for years.
• Hiding my character's race, class, level and subclass on the Campaign Page should be an option. Maybe I don't want my fellow players to realize that I'm a Warlock or Rogue. Maybe I don't want them to know I'm a Changeling
• Editing statblocks on the Extras page needs to be possible. We can override the stats of pretty much anything on our sheets except that.
• Tasha's Sidekicks currently are not properly supported. I'm aware this is being worked on, but I wanted to add it for completeness sake anyway.

Features for DMs

• Content banning. Especially when dealing with newer players, especially as a DM with an absolute crapton of character options that I share, I should be able to toggle certain sources or (better yet) certain options off. I can restrict access to Compendium entries, so why can't I ban an option outright?
• DM Screen. I currently have to use the mobile app or a third-party extension if I want to see the Passives, HP, and AC of my players at a quick glance. This needs to change. It's ridiculous that this isn't already a thing, tbh. by extension, the Campaign Page is nearly useless as-is. There is a single field for DM notes, a single field for public notes, a description, and a list of characters. That's not enough.
• Hiding homebrew items: I like to make homebrew items that I intend to award players in advance on DDB. However, the moment I make it, any player that I share my content with immediatly has access to it. Please allow us to hide homebrew items on an individual basis. This all-or-nothing approach doesn't work and can spoil players ahead of time.

Website Features

• The search function is horrible. It shows results from sources we don't have, often doesn't show the thing we were looking for. The search on mobile is much better in that regard.
• Bookmarks! Yes, we can bookmark full pages in the browser itself, but I'd love to be able to bookmark specific statblocks or rules, or even spells.
• Actual clarity on features in development. I've made this point before on this forum, but I'm going to reiterate it here: There used to be a roadmap, there is not anymore. The suggestions board is not (visibly) being kept up (the last time a suggestion was marked as anything was several years ago). The weekly updates are a step in the right direction, but watching a 20 minute video is not something everyone has time for. At the very least there should be a text version of the dev update. 
  A list of features in development or considered for development, even without release roadmap, would also be amazing. The Feedback and General Discussion boards are constantly being flooded with thread of people that are asking for the same features over and over again. Mods don't even respond to most of those threads anymore, and the developers even less. This, combined with the apparently inactive suggestions website makes it look like the developers aren't really listening to our input, no matter how much you'd like to assure us that you are. I don't want a release date. I don't even need an estimated roadmap. I just want to know you're working on it, or that it's on a list somewhere.
• The homebrew tools need a rework with ease-of-use in mind, because as they are you literally need an FAQ in another tab to properly understand how they work. They're obtuse, the terms for certain fields make no sense, the FAQ was user written, not even dev-made, and the tools are restrictive in a lot of cases. Why can't I make statblocks for creatures that the sourcebooks/adventures say simply don't have certain stats, like the animated coals from chapter 2 of TWBTWL?

That's all for now. I might add more things, but these are the ones I've had on my mind for a while. If I add any others, I'll edit this top post. Any suggestions with the "edit:" tag was added later.

I'd also add that each book in the marketplace should say what features in the book are or are not supported in the character builder and character sheets. 

I'm adding a revamp of the Homebrew tools to the list, because honestly they need fixing. They are really hard to use.

This is a good list and in my opinion it's written in the spirit of someone who loves the product and would like it to improve. Which I think is the proper way to go about these things. No laundry list of real or imagined complaints from a hater whose goal is simply to crap on something. Just a simple list of requested improvements with an eye toward usability and quality of life.

I'd add that the ability to homebrew mundane equipment beyond the "custom item" feature, and including containers has been a long-requested item for both players and DMs.