unless you're using a full set of mystic items, which im sure you're not, it is a very fair trade off
with other gear pieces, which used to be 5 and is now what...10? it more than makes up for the stats. you can customize your stats on each piece of gear to get so much of every stat you could possibly want it really isn't an issue

this is more of a problem at the very very early game when you don't really have any gear, i guess

the biggest issue with mystic gear is you can't get the specialty stats (purple/yellow/red), but even that is fine because again they doubled the amount of gear you can wear so using one or two mystics is absolutely no issue

not really, since other gear part will some time lack very important status like health regen, additional damage, or absorb, which make the trade off be much more uneven. it some time make the restrict too high, especially when the gear give good mechanic but the status that way less useful.

okay

This is a usual problem with many loot based games. Not understanding the importance of useful and unique stats on unique pieces of gear and then making them under powered vs much more common items.