STO are definitely interesting, and is one of the ways this market can be invested in for entities subjected to heavy regulation. You can probably see it as an improvement over ICOs which have nearly no oversight. I've learnt quite a bit from CoinGecko's 2018 Cryptocurrency Report regarding STO - Slide 49.

Link here for reference: https://www.slideshare.net/coingecko/coingecko-2018-full-year-cryptocurrency-report