Desh-Rae-Halra
Explorer
Because they all have a giant horses ass and poor table manners. Where do 90% of adventures start? That's right, in the smoke filled, dimly lit tavern, from the hooded guy sitting in the shadowy corner in the back. How is your 1,000 plus pound horse-butt going to get through door and then navigate across the room of tables and patrons without stepping on feet and causing the tavern wench to spill the drinks she is carrying? Plus there is the issue of random horse droppings, because you still have the digestive system of a horse.
Face it, your a walking social disaster. No cryptic quest giver in their right mind is going to trust the fate of the known world with you. Centaurs just can't get the job done, and thus are never invited to join any of the better adventuring parties.
A centaur is only unplayable if you have a phobic or crappy GM.
I'm guessing Caliban is being coy here? If not, let's consider this:
If 90% of adventures start the way you suggest, then WotC ( as well as every 3rd party publisher) could save some serious ink and pages with the adventure setup and just publish ONE SINGLE INTRO that applies to every adventure forward.
That set up is so cliche it actually bothers me that someone would use it as a defense on this specific topic.
But if we are going to go with how their anatomy doesnt fit the campaign:
- Give it a high charisma, and there will be certain individuals who want to have "relations" (see Catherine the Great )
- Who can earn gold by creating a "mechanical bull" entertainment in the not so cramped tavern
- If the DM is going to be that much of an OCD nightmare that you will have to roll a Fort save, or they just narrate, that you randomly crap yourself, then you should probably quit right there, but if that's the only game in town, then you should probably insist that everybody make rolls, or that urination/defecation checks be mandatory: Hence, the Wizard is trying to get 8 hours of rest, well oops, your bladder disagrees, start over. Oh, you have been crawling around in the dungeon for a few hours, better make a roll, you might really need to take a dump as the evil high priest is about to make the sacrifice you were sent to stop.....
Also, why the hell does anyone trust the mysterious stranger in the tavern. If it was me, I'd say lets take this guy out back and kill him, because since we are in cliche-land, there's a 50% chance that he is actually the bad guy in disguise trying to manipulate the party....or wait, maybe we could just hold him down under the centaur and make Intimidate checks (with a bonus) regarding the impending fecal consequences.....