Would it make sense to peel off paint from peeling bathtub
I'm not sure if there is a correct answer. Stripping off all the paint would be a job, especially where it may be well adhered.  I think you would be well served to remove any loose areas as they develop until you are ready to do a complete refinish. When you do the refinish, then it will be necessary to strip all the paint and etch the original porcelain before proceeding. 
.