In short:
SMT's will have all the good from Steem and none of the bad. If you're a long time user, you know what I mean or know the history. I'm sure many would like to integrate the technologies behind Steem token to power up their community but don't really want all the baggage that comes with it currently. SMT's will also allow developers to have way more control; supply, issuance and so on.
I personally know many developers who have chosen to just fork the Steem chain for their own projects, so there's demand for the technology, SMT's can't come soon enough.
Ok, so for the projects with resources (that happen to like the tech), why would they choose an SMT over just forking the chain like many are already doing?
Network effect, faster implementation, having a community of people that have interest in seeing your product succeed and so on.
Is that enough though to forego the other option? Those reasons don't sound all that tangible.
Jondoe, you're asking questions you could answer yourself with some thought and research.