Thanks for piping in Michelle! Yes, as digi scrappers we simulate a lot of paper pages, so I do understand using it on a few pages. I just think if you're actually doing Project Life, or printing out a whole year in a book, it just looks better and less weird without the digital page protector. I would use the digital page protectors as a design element on a one-off page, for sure. But a whole year's worth, not my thing. Again, just my opinion.
I don't have kids either and I love being able to put my memorabilia into my page protectors. I actually have an awesome document scanner and have digitized most of my important documents. I just find it easier to just journal, put my memorabilia in, and I'm done. Don't have to turn on the computer, scan, and all that. And with big huge items like a 18"x12" map that you get when you visit the San Diego Zoo, I love that I can just tri-fold it and put that into the page protector as well. You can't "fold" digital things and have it readily available to "unfold".
Don't get me wrong, I love digital scrapbooking and would NEVER give that up! I just find the physical Project Life products fits with my goals of having the album better.