Contrasted with IOS; phones from several generations back are able to upgrade through a fairly simple process to the latest OS. This helps insure that most relevant hardware is within a few versions of the current shipping OS, thus reducing compatibility issues.
I wrote off Samsung devices for this very reason. I bought one of the first pads and to this day there has been no upgrades to the OS on the pad. There is no reason other than forcing users into an upgrade path, that the tab could not receive a honeycomb upgrade bringing the pad up to an OS that was designed with tablets in mind.
Yes carriers would rather have you buy a new phone, but for a lot of consumers it doesn't matter. I mean seriously if it was that big of an issue you probably would of rooted your phone by now. A recent study came out that 50% of iphone users haven't plugged in their iphone after initial purchase, so basically theres a large amount of people out there that just don't care or know. The benefit of Android is that its customizable. On the other hand if people really didn't want to worry about root but wanted upgrades they should only get the Nexus phones.
Last year, I tried upgrading my phone, but they said it would cost me $200-$300 to get a decent android upgrade, so I went on craiglist and bought a G2 and a Mytouch 3g slide as my backup/music/video player for a total of $225, they had scuffs on the side, but overall were in fine conditions. I also had a G1 that i used to learn about rooting, so after i got the G2 i rooted that in 20 minutes by downloading the 1-step root app, downloading cyanogenmod 7, and flashing it to cm7.
If you want help buying a phone via craiglist, pm me.
To paraphrase Kissenger, you can't get Android on the phone. Google just releases what they release (or in the case of Honeycomb, doesn't) and it's up to the rest of the world to figure out what to do with it and how to do it.
iOS and WP7 in contrast have a coherent hardware spec and roadmap.