I had the exact same dilemma. I find it highly irritating (regardless of company that does this) when they lock down the device so you can't load your own programs on it (even when you do pay, they limit the amount of side loaded programs, at least with WP7 and the account type I had). This is one of the biggest problems with mobile phones and tablets today... you are only allowed to use them like the corporations who sell them to you say you can (as opposed to using Windows on the desktop where you can make it do whatever you can make it do without having your wrist slapped). Even iOS has this problem. There are some super cool apps on Cydia that Apple would never let you run (the kind of apps that would make me want that phone if I could actually run them without jail breaking it).
My subscription ran out a few months ago on the Windows Phone Developer site and they removed my side loaded programs from my phone (i.e. I flipped my phone on and one day and they were gone, I suppose that could have been a time limit deal also but it happened around the same time my subscription expired).
I have two apps on the Marketplace for WP7, I really have no desire to update them for WP8 (they're stable currently and don't need updates where they're at). I don't feel like going through the hassle. A free app doesn't make Microsoft any money through the app, but it does make the platform more attractive which will make them more money on that side. On the desktop, I can give away free software for free. Can't do that on the phone (I pay to give free software away). My apps are two games, obviously doesn't mean a thing to Microsoft if they disappear (I do have active users on both games which I think is very cool just because it's cool when people use your software). The bigger question is how many other people are like me?
I went from Android -> WP7 (I have an iPod Touch 5th Gen/iPad 2nd gen also so I do use iOS also). My phone contract isn't up for a few months, but I may switch back to Android (the only reason I switched away from it was I wanted something that integrated with Exchange better and I wanted to write .Net apps instead of Java). I like the text messaging/email in WP7 more than Android/iOS but frankly it's just missing a lot of apps I want (The Facebook app which does exist just sucks for WP7, it's slow and it's missing a lot of functionality found in other implementations, it's kind of a perfect metaphor for where I feel like the current state of the device sits).