I don't think people care so much about the addition of anything so much as the lack of any possibility of permanently turning it off. At least in this case, it's optional, but the related 'stuff you might have missed' 'feature' isn't.

I personally really hate this kind of thing as it clutters up my feed, and it never gives anything I care about. The value of Twitter for me come from the reverse-chronological feed, not this kind of thing.