My son is 2 1/2 and he did the same thing about a month ago. He began with not wanting to add as much water as before, then he didn't want to sit down, then he didn't even want to get in. He likes to play in the tub with his tub toys when he is fully clothed, but doesn't want to physically take a bath. After a few days of trying...I decided that he had to take a shower with me because I could only do SO much with the water hose at outdoor time! Now, he is obsessed with showers. At the beginning (for a few weeks) he would not stand up, so we had to wash him while holding him. Then I forced him to stand up out of range of the water while I washed my hair and then he wasn't as afraid of standing. Now, he gets so excited any time I walk in the bathroom. Note: We use our master shower for this activity, and when he gets more and more comfortable, we will try his bathroom again.
He is at the point where he likes to stand most of the time and play with the water because he can control how close he gets to it. When we are done and I turn the water off, he ALWAYS says "on please." He doesn't want to get out!
I think this is a phase all kids go through at one time or another. Best of luck to you!
Oh, and I forgot to mention, my son is deathly afraid of the hand shower nozzle. I tried that first and he just about lost it! Most kids like them though...