An SMT will be traded through STEEM, so we won't have a bunch of SMTs and STEEM just one of them. We will have STEEM, and then a bunch of SMTs on top of STEEM. Market-wise, this will most likely boost demand for STEEM, as a token. Also, the SMT generation mechanism is way more complex than just a token issuance on the Ethereum platform. When you launch an SMT, you literally launch a thin layer of Steem-application-processes on top of your content, including your own rewards pool, your own inflation model, your own voting and curation algorithms and your own vesting mechanism.
Hope this helps.