Based on the formula revealed in the kToS patch notes and in the reddit thread (https://www.reddit.com/r/treeofsavior/comments/3puw0d/critical_rate_formula_discussion/), we understand that the critical rate formula is as follows:
Actual Critical Rate = (Critical Rate - Critical Resist) * (42 / Character Level)
As you can see, as you level goes up, your critical rate against the same monster actually decreases due to the multiplier getting smaller and smaller.
I have run some calculations and you would need ~2.4 dex per level up to maintain the same critical rate against the same monster. Archers will need need ~2.2 dex per level due to the addition scaling with dex.
Do keep in mind that this is assuming you are fighting the same monster. If you are fighting other monsters that scales accordingly to your level, their critical resist will increase as well and you will need even more dex to maintain the same critical rate.
With that said, it seems critical builds are highly infeasible in the high levels due to the level scaling working against you and it will be hard to get enough dex to cover this ever widening gap.
To me this feels like a character build to crit most of the time (e.g. Full dex build etc) will suffer greatly in the later part of the games when the level cap is slowly increased unless there are changes to the crit formula.
Feel free to chip in and correct me if I am wrong. Cheers!
TLDR: Game punishes you with lower Base criteria rate as you level up.
