Are either of these things that could be supported in the future? If not, is there a better way to get this kind of behavior so that materialized views are more useful when the amount of data increases and it's not feasible to update them in their entirety?
The current implementation of materialized views has limitations, some of which you've listed. Materialized Views can be (and previously were) manually implemented using triggers - and you can still do so. I recall seeing some recent blog articles discussing various schemes for materialized views and their pros and cons.
That said, I'm not sure what using materialized views instead of normal tables buys you in the first place. I could see possibly using a materialized view as the current month's table but the historical tables usually don't require refreshing.
David J.