You do realize that for much of Wikipedia's history, the route to being an admin was much less strict than we have now. Despite this, and despite the fact that there are relatively very few cases of people being "de-adminned", cases of rogue admins doing huge damage are either non-existent or very rare, depending on what you consider "huge damage".
Why is it that those admins, let in under much less strict processes, have not resulted in all the nastiness that are predicted if we somehow relax the process again?
The main difference between Wikipedia then and Wikipedia now is that we now have people reading who don't contribute. Contributors know what to expect, they don't mind a little vandalism because they know how to fix it. Readers need what's visible at the moment to be right, not just something hidden away in the history. When Wikipedia first started, the only people that read it were those that contributed too, that is no longer the case. Originally, Wikipedia was made by geeks, for geeks. Now it is made by geeks for the world (for a suitable definition of geek - there are so many definitions out there, I'm sure one fits). We have a responsibility to our readers.