Using rental car as luggage storage at arrival airport?

This is a stupid question, but it's something I've never thought about doing before in all my travels.

So, I'm on a trip right now where I'll be picking up a rental car at my destination, but I might actually want to hang out at the airport for a little bit landside. (To await and have dinner with a friend who's aircrew) Is there any reason I shouldn't go through all the motions to pickup my rental car, get the key, lock my luggage in it, leave it in the rental car pickup area, and return to the terminal? If it's not a good idea I'll just drive it into short term terminal parking and pay that, but thought I'd pose the question.