That happened to two of my mates in GW1 and anet just said, in essence "tough luck start again"
They were not too fussed and did but in a full MMO if you work up to cap or get good gear or a rare title etc etc and you get hacked and they just say "oh we'll start again" I would be gutted/raging and I don't think I would be the only one.
My problem with GW1 was passwords, the daft password system in the first place but once it took them a week and another time 10 days to restore a password

again I wasn't that fussed in GW but in a full MMO I would be pretty hacked off.
Essentially my concern boils down to that I hope they don't use the f2p model as an excuse to fob people off again with bad customer service.