On this point, I think @kissane is too kind.
Mastodon should absolutely implement full-text search and Twitter-style quote posts. I suspect Eugen would agree as well.
But I also feel that these quirky product decisions happened in the first place because Mastodon did what their users wanted at the time.
And if Mastodon does a complete 180 degree turn here, it will alienate some of those old users.