WAL segments size

Hi,

One of our PostgreSQL databases is generating archive logs too frequently,
since the number of transactions/s (inserts & updates) is very high.

I was looking for a parameter on postgresql.conf to increase the WAL
segments size, but according to documentation this can only be changed while
building PostgreSQL.

Some questions came up to my mind when I read that:

1. For databases with this kind of behavior (high number of inserts &
updates), wouldn't be better (from the performance point of view) to have
larger WAL segments?

2. Is there a special reason to not allow the WAL size to be changed on
postgresql.conf (version 8.2 or 8.3)?

Best regards,
Bruno Lago