SMT's will be used for thousands of communities as they allow for new people to hold the power of that ecosystem. In Steem the stakes are already in the hands of a few. SMT's can make sure to assign power into the hands of the right people. They also invite new investors who like to support these projects. Additionally it can be partly pegged to Steem which stabilizes the new currency.
You have a good point as well and there will be many communities on Steem with the new hivemind features. There is room for both.
maybe I just don't understand SMT's well enough. I did read the whitepaper... but.. a bit fuzzy.
Every time I read a whitepaper I feel like literally staring into a blank piece of whitepaper :D But these things are mostly written for the potential investors and developers rather than the people that will be using them and helping to make it work for some reason. Suffice to say, reading the whitepaper for Steem you wouldn't think that we have all the different problems that we see here everyday, so I think it would be interesting to think about what the potential issues of SMTs might be...