Heck, I only use a fraction of the functions on most of the PICs I use in my projects. I've found that a particular family works for me, and tend to use this for similar projects as I already have the code and it makes life easy. Unless I actually need a function such as USB which is only available on a selection of PICs, I stick with what I know. It may be different for commercial projects where cost is a factor, but for hobby stuff I don't think it matters