Most of the time the stuff that gets leftover doesn't do or hurt anything though, and IMO sometimes it's actually nice to be able to reinstall a program later and not have to customize it all over again (user data/settings are often what is left behind, and generally for this exact reason)
Working tech for as long as I have, I can say with some certainty that not being able to simply drag a program to the trash is a case of protecting users from themselves. I'm honestly glad that Windows doesn't work that way. Not saying there isn't room for improvement (like making appwiz easier to get to, or enforcing a more universal uninstall process), but it's certainly not as bad as it's often portrayed.
The easiest way to uninstall programs is to reformat your hard drive.*
* I Dell tech actually told this to my wife, who has a computer science degree.