Ofcourse would another technology make things more complicated.
However, i would imagine that the Sql server would come included with a default Exchange install. At the moment you do not spend that much time tweaking the ese database either.
However, unlocking mailstores through a SQL-like interface would make managing the separate mailmessages a lot easier. And being able to split the database engine away from the Exchange interface would mot only bring real single storage, but would also require just one expertise of running a high-performance SQL server. That way the exchange admin could just focus on mailflow and configuring. (if it would still be interesting is another question)