I would consider many cryptocurrency/token exchanges more similar in functionality to a bank, than a currency or securities exchange. As soon as an exchange engages in lending activities, I'm pretty sure that puts them into a different regulatory classification. Many financial institutions offer currency exchange services, but no currency exchange services can offer other financial instruments like financial institutions can.
Good point about the lending putting an institution into a whole other regulatory class. I guess if they are regulated more like a bank, then they could have the privileges of a bank as well, including acceptable levels of fractional reserve banking, etc.
Margin trading lending may be a special case, as it's directly to traders with the trading platform being the facilitator and taking their cut, so I'm not sure if that would trigger that banking regulatory class. That may be the reason why in the fiat world, the privilege of lending to margin traders is reserved for the brokerage houses and is not available to users. While I definitely want that to be above board and safe, I do like being able to participate in that opportunity with small amounts of funds.
If an exchange is just going to be an exchange, then I would say no to any fractional reserve schemes. They wouldn't be lending anyway, as that's what a bank does, except maybe to facilitate lending to margin traders.
It's amazing how much overlap there is. I think you're right, that cryptocurrency exchanges really are more like banks or other types of financial institutions. It makes sense to get the whole banking/financial services licenses in order to operate at full capacity. I'm glad DNotes Global is aiming to get all those licenses. It will be so much easier to deal with all things financial under one roof.