Why Can't I Create a Master Page in the Site Collection???

Chalk it up to being a newbie at SharePoint v3/MOSS 2007 development, but I expected that since I was a site "owner" of both a sub-site as well as the site collection that I should be able to create a master page using SPD and save it to the site collection's master page gallery... silly me.

With some assistance from a co-worker, it was discovered that being a site owner doesn't give you rights to do this. You have to also be a member of the "Designers" group. I understand this role, but it seems odd that the "owner" doesn't have this permission as well...