I admire everyone's logic (incentive misalignment?), butm as for me, I serve the Realm. Geer, as usual, is correct. The $100 is to encourage someone new to take over a team that they didn't draft. By next year, the fact that they didn't draft the this team is much less. the "fee" is not to punish anyone or to keep disinterested owners in the league. A disinterested owner is much worse for a league than dropping out.
Ed- you're right too that you are encouraged to find a person who costs you the least, but the fact that you have to find someone who wants to commit to at least three years and pay $175 means that you will likely find someone into fantasy football where they would make the league more more competitive and fun. It also seems unlikely that someone would be willing to make that commitment also to play in a league with a bunch of people to whom they have no connection.
But the main incentive (which seems to be working) is the general desire not to screw people over. The fee is needed when someone drops out a week before the draft like a jackass. Not Ed in this case, who made sure not to screw us over too much and told us early, giving an opportunity to find a replacement. And (presumably) we don't want to make Ed pay $100 when we have plenty of time to find a replacement.
Without knowing why Ed wants out, ideally he could find someone to split the team with him and do the football stuff while still being part of it. Or even more ideally, he could find an "Andy-like" owner who is really involved and committed but not very good.