Public transactions are unacceptable in regulated markets. Think about the consequences of moving millions on an exchange wallet. Even without selling a single asset, just by broadcasting such a tx on an open ledger you can manipulate the market and induce panic selling in a way that is completely illegal.
Public transactions would be a problem in regulated markets, i can understand that but how about semi-public transactions.
Like 7 days or 15 days, later transactions can be seen. No-one can manipulate the market this way and it also keeps the blockchain transparency intact.