As a mom to a 2 1/2 year old boy, I can tell you just one thing for sure: the only thing predictable about toddlers is their unpredictability! My son has gone through loved/hated baths, refused/alllowed/refused/allowed hair-washing, gobbling breadsticks like they were candy/rejected every breadstick known to man, obsessing over Yo Gabba Gabba/hating Yo Gabba Gabba...you get the point. Just when I think I know something absolutely, positively, sure-fire about him, he changes. Then changes back. Then throws me a curve ball from a completely unexpected direction. I've kind of learned to say "at this moment" about things: "He loves spaghetti, at this moment".
Maybe try alternatives to the bath tub: shower? sink bath? (a personal favorite of my guy during a no bathtub phase) Sometimes you just have to say "whatever" too. Your 2 year old probably doesn't need a bath everyday.
My son also loves these Crayola color tablets (you can buy them at babies r us or toys r us in the bath aisle--get the Crayola brand though not the ones with Sesame Street Characters because they smell like old lady perfume and make my son sneeze every time he opens them) that you add to the water to make it colored. I do worry a little about bathing him in food coloring, but it gets him in the tub when nothing else will (and seems to cause less skin irritation than bubbles).
Best of luck to you!