Rogue Fixed? Or Broken?

I was thinking about how the Rogue is often regarded as the weakest of the Martial classes. I wonder if they truly are a Martial class, or if they are actually a "Skill" class? And perhaps they are supposed to be weaker in combat than the Barbarians, Fighters, Paladins, and others? 

But let's assume they ARE a Martial class. Let's assume that Rogues DO need a boost to compete with Fighters, et.al. Given those assumptions, I had an idea for a "fix". We address the Rogue's damage and defense with two simple adjustments:

First, on defense: let's give Rogues their proficiency bonus added to their Armor Class when wearing only Light Armor and no shield. Leather and Padded Armor give a base AC of 11, and Studded Leather gives a 12. Most players will have a +3 to Dex in early gameplay. Some may have a +4. That gives an AC range of 14 to 16. Which is ok, but not great. Adding Proficiency to this will increase that AC range to 16 to 18. And it will help Rogues have an AC that scales. Dexterity caps at +5 until Epic levels, so, excepting for magic armor, Rogue AC caps out at 16 or 17. With Proficiency, that would increase as they level, until they maxed out at 22 or 23 (11 or 12, +5 Dex, +6 Proficiency at the highest levels). Obviously, magic armors would boost this by an additional 1 to 3. But that still isn't unreasonably high, if you consider some of the ACs achievable by Artificers, Paladins, Fighters, etc, when they have full plate plus a shield- especially if those are magical. But idk... maybe this is too much. And of course, one could easily argue: if Rogues get Proficiency added... why doesn't everybody? I mean, they're all proficient at wearing their respective armors, so... why not? Yeah, idk. Because Rogues need the help more, I guess?

Anyway. Offense: quite simply, give Rogues a second attack at level 5 like every other Martial. And let them use their Sneak Attack on both attacks, so long as both attacks meet the normal prerequisites. It should be made clear thst Rogues could only apply their Sneak Attack to attacks using the Attack Action, and not to any attacks made using their Bonus Action. And maybe we'd need to eliminate their ability to Sneak Attack on their reaction, to balance things out. Maybe not. Then, at a higher level- say, level 15 maybe- Rogues could then also Sneak Attack on a Bonus Action attack for up to 3 Sneak Attacks on the Rogue's turn. Although, that might be getting too ridiculous.  You'd be looking at like 24d6 (72 average damage, with potential for up to 144) at level 15. And then if they were to crit... well that's just broken. So maybe not with the 3 Sneak Attacks. 

At mid level tiers, we'd be looking at 6d6 to 14d6 of Sneak Attack damage, assuming 2 hits with 2 Sneak Attacks on a turn. That's not actually that crazy high, considering Paladin's Smites, Barbarian Rage damage, Fighter's multi-attack & Action Surge, etc. But then again, maybe it IS too crazy-high damage. Idk. Probably. There's also the concept of increasing the potential pool of d6's available for the Rogue to spend on Cunning Strike options- as well as the ability to apply two Cunning Strike options in one turn. And then FOUR at level 11. And that is another whole can of worms.

Anyway. It was just a thought that I had, and I thought it'd be interesting to see people tell me how broken this probably is. But also to see if anyone has other ideas, or adjustments to these ideas. 

Rogues are NOT the weakest martial class, they are one of the strongest. It is frequently said that Rogues make better fighters, than fighters. Paladin smites are a limited resource, and unless you play where there's only one short fight per day, the Paladin always runs out and can't smite every round. Same with the Battlemaster. I'm not knocking either, they are both solid choices and good at what they do, but what many fail to take into consideration, is that the Rogue can Sneak Attack EVERY round. They can also generate their own combat Advantage, EVERY round (Hide as bonus action or use a Vex weapon) or they can choose to Disengage and move out of enemies' reach, EVERY round. Now, whether they chose to do so, is up to their style of play. The Fighter or Barbarian with a two-handed weapon, needs fighting styles and feats just to keep up (and pass) the Rogue's damage/round - but dpr isn't everything, the Rogue's mobility during combat and amazing skill array (as well as relying on a single ability score, Dex, for almost everything they do - hands down the most influential ability score in the game) makes them more survivable.

Their AC tends to be a bit (not too much) lower than a Fighter or Paladin for most of the campaign, and their hp are akin to the cleric not the Fighter/Paladin/Barbarian - but they aren't meant to stand in one place and trade blows. The move in, strike, and move out or sneak attack at range - something they are very good at. They don't target a foe 1v1 (unless they're a swashbuckler), instead they target whomever is in melee with any ally. I'll take a pair of Rogues in the group over a pair of Fighters any day.

In my extended group(s) Fighters are a dying breed. As in, they die - first, often, and repeatedly, while Rogues live forever. One particular DM in our extended group is known for difficult fights that can drag on for multiple game sessions (yes, even in 5.5e). Today is game 4 of one such fight. In games where short rests are a luxury, classes like the Rogue truly shine. In fact of that 6 PC game, 3 are playing Rogues or Rogue multi-classed characters. 

Until the Fighters get to 11th level, Rogues tend to get more attacks per round (due to their use of Light and Nick weapons), which means more chances to crit, and can easily Sneak Attack at least once every round (made even better by those extra crits). They aren't likely to be hit by Opportunity Attacks, and since they don't stay in reach of the baddies long, they tend to take less damage and have excellent chances of escape or repositioning (any rogue can move 90' / round if they want to).

In a 1v1 fight between a Rogue and a Fighter, unless it's in a tight hallway, the Rogue is likely to win.

The only way a Rogue comes up short, is if they stand in one spot and try to get themselves killed.