Realistically, the only trouble you're going to run into with an unfinished body is the accumulation of sweat, grime, beer spillage, hooker dust, etc. This is true of just about any wood species you might make a body out of. I suppose a really soft species might be more prone to breakage, but for any lumber that's sufficiently seasoned to be stable, you're not likely to run into the same kind of warpage risks you see with maple or mahogany necks, for example. When push comes to shove, it's just a lot easier to wipe off a hard-finished body than to attack it with sandpaper or steel wool or a scotchbrite pad if it gets any scuzz on it.
In short: You won't run into any issues that compromise functionality, but your guitar may get a little gross. Look at Stevie Ray Vaughan's No. 1, Rory Gallagher's axe, etc., for what happens when exposed lumber gets played for a long time. it turns grayish brown from built up gunk.