Breakpoints are gone (except for the gcd, but w/o haste aura and NG we probably wont be able to reach that anyway), but values still change depending on other stats. The more you have of a stat, the more damage you get from all other stats.
Example:
Let's say multistrike is always a 1% increase per point you get, since it's basically just a damage multiplier that doesn't interact with our rotation at all.
Just for this example, let's ignore that fact that crit grants extra chance to give SS procs. This basically just makes it a damage multiplier aswell. Let's say 1 point is a 0.9% increase here.
If you had 100 dps, and 0 multistrike and 0 cri (no base crit either just to make it easier)
1 Multistrike would give you 100*0.01 = 1 dps,
1 crit would give you 100*0.009 = 0.9 dps.
Now if you do 100 dps without any stats at all, if you gained 50 multistrike you would gain 100*0.5 = 50 dps which is a 50/100*100% = 50% increase, or 1 dps per point of multistrike. At this point, you get the option to choose between an aditional 1 multistrike or 1 crit. Choosing multistrike would give you a total bonus of 100*0.51 = 51 dps, so the bonus from that one point would be 51-50 = 1 dps. Choosing crit would give you 150*0.009 = 1.35 dps.
tl;dr: Stats stack multiplicatively with each other, but addictively with it self. Thus, the more of one stat you have, the less is it's relative value.