I believe that an MMO can mature over time and provided that the developers don't make fatal mistakes (which seems to happen more often than the industry seems willing to admit) it can blossom into something no one could have predicted in those early days after release.

Having said that the MMO community is built largely around momentum and word of mouth and that first month is so utterly incredibly vital in that respect that irreversible damage can and has been done. They key thing here and I know that this is probably an obvious comment but from the recent releases it makes me wonder: is the game good? You can have a bazillion features and a bug-free launch but if the game simply isn't fun then your goose is cooked; the old polishing a turd analogy works pretty well here and if you think the community at large won't call a turd a turd you are delusional.

As unforgiving as the MMO community can be if you release a game that is genuinely good from day 1 they will forgive many, many other shortcomings.