Guild Wars 2

Confused why we have a bow spirit weapon but are unable to use any bow for a weapon instead of the staff or scepter. Are we getting bow in future update or something?

Your argument makes no sense. By your logic an elementalist should get access to bow/axe/hammer/shield. Hell, anyone can pick up those conjured weapons, so they should be available to all classes, no?

I would advise you to join the conversation in this thread: https://forum-en.gw2archive.eu/forum/professions/guardian/Guardian-with-longbow/first which already discusses ranged options for the guardian.

Bow probably looked more visually appealing.
Alternate hypothesis: Somewhere in the development of the game, Guardians actually had a bow (or Spirit Weapons worked like the conjured weapons of the Elementalist) and it was removed for some reason.