As another poster noted above, I'm trying to cut down on diet sodas in general, but I prefer the caffeinated varieties when I do drink them. So there you go--I'd rather go with the caffeine.
When it's not available (literally--only at BYU), I just drink something else. It isn't a tremendous deal to me and probably healthier anyway.
What I do find annoying is that a relatively few who want to interpret LDS policy a certain way and feel everyone else must be bound by their flawed interpretation get to make the rules. I don't like it in general when people feel compelled to legislate their morality on to everyone else, and this is a particularly petty and grating example.
It also makes us look that much more weird to outside visitors. One more strange rule to explain--this one not being grounded in anything really.
There's nothing you can't do, no office you can't hold in the LDS church while maintaining a habit of drinking Coke, Pepsi, etc. But at BYU, we have to special order this non-caffeinated version and limit everyone's option to that. Why?