I'm not sure how valuable this is before T5873, but I don't think it costs us much either. Your call either way.

Offhand, I imagine we'll probably end up with full-power endpoints (say, app.xcreate, app.xupdate) which take a list of transactions to apply (and, in the case of xupdate, an ID to update) and get full access to every possible transaction. And then maybe we'll have easy endpoints (say app.create, app.update, app.comment) which take a small list of things like "title", "content", etc., and build the transactions for you.

However, I'm not sure how valuable the easy endpoints really are, or if we need them. If we do, maybe we can get away with a few shared ones (like anything.comment which takes a PHID to comment on) and not have per-app create/update easy ones. So it's possible that after T5873 we might want to deprecate this kind of endpoint and just provide fully transaction-aware endpoints (which can presumably be very simple). Not a big deal regardless, and I don't have strong feelings about either choice being preferable.