"You've never seen cabinet doors with glass inserts? "
Heh, Don, you moron. Of course we've all seen cabinets with glass inserts. I didn't say they didn't exist. I said YOUR suggestion of simply changing the doors on his existing builder cabinets to glass ones makes no sense. That's because, as I already pointed out, cabinets with glass doors have inside finishes that are attractive, usually the same as the exterior, and meant to be seen. If you replace the doors on typical builder type cabinets, which is what this person has, with glass doors, all you're going to do is look at an unattractive inside of a cheapo cabinet.
Is that so hard to understand?