I definitely didnt expect it, nor did I expect that there would suddenly be more than a dozen different apps. But its not a problem, the more choices users have the better. Those who like such clients can use them, thout it affecting anyone else. Plus monetization of apps could potentially help to fund development of Lemmy itself.

For instances with ads its pretty much the same, more choice for users. But I really doubt that model can have any success considering how many free instances are around which are run by volunteers. Defederation should be unnecessary assuming that ads are only shown to local users.