i wouldn't say no one acheives anything, nor do i recall any comments bashing it, most were just people being legitimately critical off it, and are backed up by some very knowelegable experts in the fitness realm, so i really wouldn't say they're uninformed either.
the problem, that needs repeating, is with the explosion of its popularity there are an increasing number of poor trainers and gyms getting into the fray.
there are good trainers, as you point out, that use some methodology and don't push people to injury. some crossfit gyms and trainers are a recipe for injury though, and crossfit national as a program should start doing something about it, it's not as easy a chaulking it up to poor trainers soley, the program (or lack there of) needs some rethinking.
i say this having done cross fit. i tried it about five years ago are a gym on carlaw that had very knowledgable trainers. i see the group dynamic as being a big motivator for some as they simply wouldn't or don't workout solo. for me i prefer working out alone or with one person, and i was already incorporating plyometrics, weight training, calisthenics, only with better methodology than most crossfit programs i've seen, so i didn't see any benefit for me personally. i will say crossfit for beginners is tricky as they generally don't have the stablizer or joint conditioning to perform many of routines without risk of injury, which is why it would be important to be part of a program that recognizes that.
periodization (rarely looked out in crossfit routines from what i've seen) is key and varying your routine is important (done in crossfit but it's not necessary to change every day though).
it's not like it's the first or last workout fad that's built on shaky foundation. overtime, i think it will become more structured and the bad elements will get weeded out.