Time limit on boss rush is beyond ridiculous. 

The game should award players for their skills and gameplay. 

What is the point of progressing our character, if we can not challenge ourselvs. 
So now you want us to get 16000 CP so we can one shot the boss like every other boss.

This was a pretty good solution to a problem. Not all classes can kite a boss around and push up to lvl.99. Skill and exploits are interchangeable here, it's their game, we are playing their vision. When we find a way to do something unintended they have every right to fix it. I'll have to find a new strategy to use with my ranger.

How is this a good solution to a problem?
You have an old player base that has completed various boss rushes on lvl 99 now, that has claimed the rewards and are miles ahead of every other new player. That has not had the chance yet.

Yes, there were classes that struggled with completing boss rush at lvl 99. HOWEVER recently iv'e seen every class on youtube to be able to do it.
Warrior, Raven, Huntress, Giant, Valk, witch have all been able too, and there are videoes of this on youtube.

Not only was this something to aim for, for newer players. But also P2W people who had higher CP had somewhere they could challenge themselves with, and it was a nice change of pace for everyone. 
The game is becoming too "auto" and a lot of stuff that F2P could do to advance has been nerfed, or taken away.
From what I have read as i'm a new player to BDO mobile, people used to farm "Violent" mobs like in the PC version. But this is not a valid option anymore as they drasticly nerfed the drop rate of the red chest. 
Now they take away boss rush, which takes away a challenging aspect of the game and makes this on par with every medicore mobile MMO out there that has a time limit on most things. 

What was amazing about this game was that there is no stamina to complete stuff, you can grind and play for as much as you wish. 
Personally I don't care that they add tons of P2W features into the game, like lets say the 600 GRAND black stones for 1200 PEARLS thats over 2Billion in silver value for 30$ in our server, that can be purchased 5 TIMES. Which is totally insane considering the original grand black stone pack has 30 in it for 300 PEARLS 

But yet they think it's a great idea to add time limit to  boss rush where people needed to grind and learn the mechanic of the boss. WHICH is actually not easy, and actually takes a considerable amount of time,  not to mention you have to get to the lvl 99 of the boss as well which can be a frustrating grind.

I felt if they wanted to add a time limit it should be at least 15-10Min long. This will still reward players that play skillfully, and it will hurt abusers who try to "Glitch" the boss. 
A time limit of 3 min. Makes this a CP thing now, and removes the whole fun of "boss rush" as if you have the required CP you may just as well press "auto play" and you will win.

So tell me what is the point of playing a auto simulator, where your only reward is there if you spend money?
And if you don't you are gonna be months or  years behind everyone else who did.
Because I don't know about you :) but 600 Grand black stones x 5 = 3000 of them. So with just a little cash you can easily just cash in over 10Billion of silver value. For a F2P to get to the lvl where he can grind efficiently and then the time to get that amount of silver while keeping a steady progress is totally nuts.