I can understand why Summon Monster started the way it did; less to code and add in and it was easier to get more done.
Now it has been awhile and many people play and I think it is time for the Summon Monster spells to get an overhaul? What kind, you ask?
Well, I think that, when you set the spell in a tavern or rest shrine, you should be able to pick the type of monster summoned, as listed in the PHB, as proper for each level of the spell.
Heck, you could even add some special ones in the DDO store that may only be listed in PHBII or somesuch!