The problem with allowing applications to talk with a database the same way they talk to an object or web service isn't so much about translating the mismatch between JSON and relational tables or tabular row-sets, but rather that the application programmers often fall into this RBAR (row-by-agonizing-row) pattern. They fetch one "entity" or "document", process that, and then fetch the next. As a DBA, you still have emphasize to them the importance of fetching everything that you need, and only what you need, in one call.
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho