I was thinking about Terra/Luna and I think that one potential problem for achieving mass adoption is the lack of privacy. For example, if I were to send some Terra to a friend, I might not necessarily want them to know my wallet address both for general privacy/security reasons. A concrete example would be a group of friends went out for dinner, and someone paid the bill via credit card first and asked the remaining friends to transfer cash to him. Using traditional finance, it is easy to transfer money via bank transfers or other non-blockchain digital wallets without revealing my previous transactions/account balance. However on Terra, this currently is not possible (to my knowledge).
I’m not sure what the solution is, but I do think it is something worth discussing about. Currently on Ethereum there are some privacy protocols such as https://tornado.cash/ etc, althought I feel the UX is still a bit clunky.