Good points both. As for Protopic, because of its application on a mucous membrane and potential for accidental ingestion, I personally will never take that risk, but everyone has to gauge the risks they're willing to take while they experiment. If I took that risk, I would make sure that was the only experiment I was trying, and I would wait a while after discontinuing it before doing anything else, so that it would be clear one way or the other if the effect was beneficial or detrimental.
As for leaving the crust on, my recommendation is when people ask about it, or tell you to use chapstick, you can reply honestly, and say "I have chronic dry lips, chapstick is useless/makes it worse." Most people let it go at that. We ought to do our part to dispell the myth of chapstick being a long-term solution. Also, I think unless you have an infection, leaving the dead skin on protects the skin underneath from environmental aggravators which might lead to infection. But microorganisms might be feeding on the dead skin as well. It could be a fine line.
You certainly don't have to say how agonizing it is for you or that it is potentially incurable, just be matter-of-fact and act like it's no big deal. I rarely have to say anything anymore, it's mostly kids who are right up in my face who notice and say something. I just say "thanks, I know," or "yeah, I have dry skin/lips." In the grand scheme of things, it isn't a big deal. We are actually very fortunate.