There are social and engineering issues around why this (more frequent releases) doesn't work well.
Imagine you're an exchange. Do you want to be forced to reindex the blockchain and deal with burning time on sysadmin stuff every month for some coin that might not yield you a lot of volume yet?
More than 4-5 hardfork per year would really be pushing it. Also, we coordinate with the community to make sure that we are all headed in the right direction together, and these discussions about specifics don't happen overnight.