I generally agree - it's mostly a UI as a service (although, there might be some economics of scale there since not everyone can buy 100 Apple stocks at a time), but there is one aspect that I think is unexploited: the pre-sell.

Essentially I know a lot of retail investors that if you told them "Would you sell this stock if it went up by 20% in the next 6 months?" they would answer "yes" and they might even put in a market limit order ahead of time, but they don't ever sell covered calls. A nice interface for this could really help retail investors.