Autovacuum / full vacuum

hi,

I'm curious as to why autovacuum is not designed to do full vacuum. I
know that the necessity of doing full vacuums can be reduced by
increasing the FSM, but in my opinion that is the wrong decision for
many applications. My application does not continuously
insert/update/delete tuples at a constant rate. Basically there are long
periods of relatively few modifications and short burst of high
activity. Increasing the FSM so that even during these bursts most space
  would be reused would mean to reduce the available memory for all
other database tasks.

So my question is: What's the use of an autovacuum daemon if I still
have to use a cron job to do full vacuums? wouldn't it just be a minor
job to enhance autovacuum to be able to perform full vacuums, if one
really wants it to do that - even if some developers think that it's the
wrong approach?

Mike