I homebrewed these monk abilities to make them scale better at later levels, and allowing the monk to keep their flavor (deflecting missiles, using ki, and hitting hard):

Martial Strike

Prerequisite: Monk, Level 3

Starting at 3rd level, your mastery of martial arts allows you to enhance the power of your attacks, whether using your unarmed strikes or a monk weapon. When you hit a target with an unarmed strike or a monk weapon, you can spend ki points to cause the attack to deal extra damage to the target equal to your Martial Arts die per ki point spent. You can use this feature a number of times per turn equal to your proficiency bonus.

Ki Deflection

Prerequisite: Monk, Level 5

Starting at 5th level, your mastery of ki allows you to deflect not only physical projectiles but also the energy of ranged spell attacks. When you are targeted by a ranged spell attack, you can use your reaction and spend 1 ki point to attempt to deflect the spell.

When you do so, the damage you take from the spell is reduced by 1d10 + your Wisdom modifier + your Monk level.

If you reduce the damage to 0, you can spend an additional ki point to deflect the spell's energy back at the caster or another target within 30 feet. To do this, you must make a ranged spell attack using your Wisdom modifier for the attack roll. The deflected spell deals damage equal to the amount reduced (the total damage you avoided) and counts as a Monk weapon for this attack.

Ki Surge

Prerequisite: Monk, Level 8

As an action, you can regain all expended ki points. When you use this feature, you gain one level of exhaustion. You can use this feature once per long rest. You gain an additional use of this feature at levels 11, 14, 17, and 20. Each additional use after the first in a single long rest incurs an additional level of exhaustion.

Reactive Deflection

Prerequisite: Monk, Level 11

Starting at 11th level, your reflexes and ki mastery have reached a level of proficiency that allows you to defend against multiple threats in rapid succession. You can now use your Deflect Missiles and Ki Deflection abilities without expending your reaction, up to a number of times per turn equal to your proficiency bonus.

After using this feature, you cannot do so again until the start of your next turn. Any additional uses beyond your proficiency bonus in a single turn still require your reaction.

A few critiques:

• I don't think "hitting hard" is really a monk thing. They are more about increasing damage through making more attacks with Martial Arts and Flurry of Blows. I also don't think one die of damage is a great trade for a ki point compared to the other things you can do.
• Ki Deflection is a cool idea, and I'd have no problem with it if I hadn't played quite a bit of high-level monk. Once you get Diamond Soul you become a defensive powerhouse. Like to the point where it's your primary thing. Between that and Evasion, I would emerge unscathed from magic-heavy fights even when the rest of the party was in pretty rough shape. To that end, I don't think monk needs more help in this area.

In my experience, monk has two main pain points:

1. There is no significant baked-in damage increase after level 5 to allow them to keep up with other martials.
2. Too many monk features require ki points, so you run out and then just kind of drag until you can get a short rest.

For #1, I think scaling FoB helps a lot. Add another attack at 11, and maybe one at 17 (haven't tested that one yet).

For #2, I had two houserules:

• Step of the Wind should not cost any ki. As a monk, you can always use your bonus action to punch via Martial Arts or run fast via SotW.
• Starting at level 3, once a day you can meditate for 1 minute to regain ki equal to your proficiency modifier. While meditating, you are immobile and incapacitated.

Those three changes made a big difference in our group.

You make some good points. Using Ki Points to deal more damage might seem steep due to the Ki economy during battle. That is what Ki Surge was all about but I understand if getting a level of exhaustion is too much. As an alternative, I created this homebrew, Ki Recovery. Potentially it could replace something like Stunning Strike (I think its a good tradeoff). It kinda works like "Arcane Recovery". With better Ki Economy, a Monk can use the Martial Strike without worrying about a lack of Ki. And thematically, it makes sense; imagine a Monk channeling their Ki into a punch in order to break a wall or hit the BBEG:

Ki Recovery

Prerequisite: Monk, Level 5 

Monks can learn to tap into their inner reserves of energy through deep meditation and focused breathing techniques without needing rest.

If you do not perform any other action on your turn (including movement, bonus actions, and reactions), you can choose to enter a meditative state to recover ki points. At the start of your next turn, roll your Martial Arts die, and you recover a number of ki points equal to the result.

However, this recovery is fragile. If you are attacked and take damage while attempting Ki Recovery, you must make a Concentration saving throw (DC equal to 10 or half the damage taken, whichever is higher). If you fail the saving throw, your Ki Recovery is halted, and you do not regain any ki points.

You can use this feature a number of times equal to your proficiency bonus per long rest.

I like it!

In the Epic Ruleset Monks get the ability to use an action to regain their Ki points, its useable once per long rest and at level 25 2x per long rest - it seems like such a basic fix if I had a monk playing in a regular non Epic Game game I would just allow them to do that - 1x per long rest level 1-10 & 2x per long rest level 11-20. its the simplest fix can be done in or out of combat and honestly monks are still way down in the overall power meta so there is no harm.