I don't really get the argument here, even if a Turtle could tank all the bosses we have right now in 60 cap not many Turtle's will have the gear to do so. Meaning if attack speed % became useless in PvE today, the majority of the time Turtles would not take the role of a tank. So yeah PvE would be pretty damn organized like in 55 cap.
Now a good argument is buffers taking the role of a SK/DW in PvE, this will be a difficult task to balance out. Also, that would actually be a lot more common since it's much easier to build a buffer tanky than a human class. Even then though, much more people will still be accepted to parties (meaning more players playing the game) than this strict attack speed % gimmick we have.
How about changing party system without need to change too much PVE system?
That is, since unlike any other MMO's, here is really problem that there is not determined roles in party soo make it that:
1. slot - Namekian Tankers ( DW, SK)
2. slot - DPS ( Fighter, SM, Turtle)
3. slot - CC ( Crane, Plasma, Karma)
4. slot - Healers ( Dende, Poko)
5. slot - Buffers ( Ultimate majin, Chef majin) / Semi Healer (Poko)
With this system, you couldn't make party unless you use those classes that system ask for.
I think it's fine that other classes than sk/dw can tank bosses if they have op gear. That should not be a problem. But nerfing atk speed would suck because crit does nearly no dmg right now. You would jump from 2 mins per boss to 10-15 mins. That would be no fun.
Well roles are made for reason, then if every class can tank, lets then buff all classes to be DPS...
What is point to have tanker in game, if no one use it.
What is point of DPS classes, if you only pick one.
PVE system needs to change or players who simply can not enjoy PVE content, will stop using those classes and in worse case they would quit the game.
Changes about CCBD:
Now about about CCBD, if this system would be added, there should be option that each time you beat boss, you choose reward you get ticket of that floor where you took reward, soo you can continue next day.
Since we all know that CCBD takes long and sometime you can't reach that floor, where you stop, you should get ticket that would be binded, and from where you can continue for next floors.
Mostly, new people who try this dungeon, get a bit tired of it and want to continue it next day, soo if it can be added, it would be indeed cool stuff.
About attack speed:
Before I suggested that bosses have some immunity soo that CCBD would be some fun and later on that feature is added.
What next should be added is that some bosses are immune to auto attack, that would mean that they would have shield that absorb 500-1000 dmg, making auto attack useless and ofc, I am not sure is it dodge rate of bosses fixed, they shouldn't dodge a lot.
PS: I want to Sirab that he come up with really nice thread that would help CAP 60 and 70 and change game for better.