Most people seem to not want to be discoverable with the exception of artists and other people who want to make money, I doubt search will replace hashtags as the primary discovery method
They were swapped before, and were recently changed to this for Lemmy compatibility, but things like the algorithm and reputation counting haven't been updated yet.
I think boosts have potential to be used for crossposts, and the current implementation are just crossposts to your profile. Though they're likely here right now just because Kbin is a mix between thread and microblog software