Although optimizers are a valid subset of players, I think they're a pretty small minority. Given the overwhelmingly positive reaction to monks, I don't see nerfing them because of fears that wizards or sorcerers will take a 2 level dip. I also don't think it would be that great. Yes, they can take the dodge action plus an unarmed strike bonus action at level 1 (so 6.5 average damage on a hit); that doesn't seem gamebreaking. A two level dip would allow a wizard, say, to take dodge/disengage as a bonus action twice before running out of discipline points; again, that doesn't seem gamebreaking.
Dodge (plus disengage) as a bonus action is far more powerful than just disengage as a bonus action. Like 5 times as powerful.
Keep in mind that ki recharge on a short rest AND they recharge when they roll initiative once a day. So it is not twice a day, it is twice per short rest plus 4 more times a day.
The point that you can dodge and attack resource free all the way from level 1-20 is true but not that great.
For a caster it isn't, but for a martial that can stun someone with their one bonus action attack it is huge.
If you are doing it resource free, all you are getting is dodge plus one unarmed strike, even at level 20 (average 11.5 damage at level 20). Which I think we can agree is not exactly terrifying.
As compared to another martial that can only dodge resource free and not attack at all.
A Monk's power is not now and never was in the damage they can do in a single round and control beats damage every day. At early levels, before they have a lot of ki they, this is a big buff. At later levels when they can spend ki at will it plays into the strengths extremely well.
We play tested this and it was WAY over the top for a martial. Not just a little bit, a lot, especially when you consider unarmed strikes can grapple/shove and this is now a save not a check and thereby automatically failed when stunned.
To illusrate how big the difference is - A 6th level dex 16, con 14, wis 18, AC17 Monk with a +1 spear and a 6th level AC20 fighter with a longsword+1 and dueling both go up against a Vrock:
The Monk is going to start using unarmed strike as a bonus action and try to stun. If he does stun, he uses extra attack for grapple and shove immediately (automatic success if he hits with advantage due to stunned condition). If he misses on the bonus action attack or misses on the stun he will dodge. Once grappled and prone he just wails on the prone grappled Vrock with extra attack and martial arts until it is dead, (still using stun once a turn if he hits on his bonus action while he has ki).
The fighter will use his +1 longsword with extra attack, dueling and a 20 strength and use action surge the first round.
This is one-v-one and is a "deadly" encounter for a 6th level character. The difference between these two is huge - on average that Monk will lose 44hps putting down the Vrock. The sword and board fighter will lose 80hps on average (assumes he has someone heal him mid battle).
This did not consider either the Vrock's screech or the poison cloud and assumed both Pcs won initiative. If I considered these it likely means death for both PCs if you consider these other abilities, but with good (lucky) saves here the Monk wins this fight more often than not and the fighter almost never does, even with good saves.
This is using baseline classes without considering any sort of optimization you could bring to improve this.
Stunning strike got nerfed to one attempt/turn in the UA, which I think was needed.
Stunning strike now does extra force damage on a successful save, which is a pretty big boost.
The extra damage aside it is still not a nerf at all until very high level when you can spam stunning strike without running out of ki.
When combined with the new way the bonus action works, this is actually ideal while ki is limited and when combined with the bonus action it is STRONGER than it was. You make your bonus action attack first and then choose your action knowing the results of the bonus. If you don't stun the bad guy you don't take the attack action (and you still do the extra force damage if you tried SS).
This is perfect for rationing resources and hit points. If you don't hit at all you don't use any ki and can dodge. If you hit and use stunning strike and fail to stun you still get the extra damage and can still dodge. If you hit and stun you can go nova unleashing your full compliment of attacks.
Also there is a DM rules question in play in here. It is not clear RAW if you have to fully resolve the unarmed strike before the stunning strike. Stunning strike only says you have to "hit". If the DM lets you resolve the successful unarmed attack after stunning strike this becomes even more powerful, because you hit with your bonus action and if you stun then you can choose to grapple instead of doing damage. Then you automatically succeed on this grapple as he automatically fails strength and dex saves due to the stun. You can then use your extra attack to prone him (again automatic success on a hit with advantage). Now even when the stun wears off the enemy is grappled and prone, he is attacking you with disadvantage even when you are not dodging. You can drag him into a fire or something using only your movement (which is high because you are a Monk). This is on one ki with a failed save and even if the save is successful you still did extra damage and are dodging.
I very much disagree that monks are currently fine! Player consensus on the monk class has been very clear since 2014.
Player consensus is flawed. Post-tashas, Monks are weak (but still viable) in tier 2, I will agree with that and it is where the core of the game is played so it probably has undue influence. They are not weak in other tiers compared to other non-casters and they are the most powerful non-caster at high levels (14+) by quite a bit.
Also this started because you asked what I don't like about the new Monk and these are the things I don't like. I prefered the 5E Tasha's version of the Monk and I have played that Monk to 20th level.