I believe it was implied that you were allowed to change your character as long as the concept and the character itself stayed the same. If the group really is full of players that value the story and the roleplaying then they will probably not make changes which are that drastic. However, if Data's player realized that he was never using his Andorian Empathy feat and he wanted to swap it out for the "Ability to use my severed head as a stapler" feat, or maybe the Vulcan Neck Pinch feat, then sure, those still fit with the character, so go ahead. (Data may not be a Vulcan, but I could see him learning this move. It fits his style.) But if Data's player is really into the character he would probably not even try to pick up bat'leth proficiency unless there was a good RP reason for it, and he certainly wouldn't be replacing "computer lore" with it.
LOL. OK, point taken.
I just don't think the need to rewrite is much different in an infrequent campaign (which is what I run) versus a frequent campaign. I guess it depends on whether the players are spending the 3 months between sessions thinking about their character's abilities, or not. In my experience, people don't really think much about it during the non-playing periods.