The problem is it's hard to have a security tokens as certain countries prohibited their citizen to buy or hold security tokens. Exchange that use security token will obviously lose many users from big potential countries. Exchanges do business and it's fine for them to get bunch of money from their users as profit. Anyway, traders would choose exchange with lowest fee, it means we don't really be afraid of exchanges' profit, and we don't really need this dividends.
Along with peoples going for exchanges with lowest fees, i think peoples would also love to invest in Dividends or Interest based coins which has the potential to make you have a stable income. If you want to be rich in the future, there are few things which you should start applying now onwards. Rich peoples would never work hard to earn money but instead they would calmly sit down and watch their money growing.
Also considering the fees, peoples trading smaller amounts are in strict need of exchanges with lowest fees. There usually is risk for small amount traders that they might loose all their earned profits into the fees so fees should always be given priority to make yourself earn profits.