INSERT/UPDATE/DELETE Views

Hi

I'm relatively new to PostgreSQL. I was wondering why were
INSERT/UPDATE/DELETE view diabled in PostgreSQL? Other database systems
have these features so why shouldn't PostgreSQL. I did some searching
and found that prior version 7.1 or 7.0 these features were in fact
enabled. I couldn't however find a satisfying reason for the removal of
these features from PostqreSQL mailing list archives.