[citation][nom]epdm2be[/nom]MSFT has already screwed over everybody who 1) ever invested in Windows Mobile 6.x in the past, 2) screwed everybody over who adopted WP7.x.And probably will screw over everybody with WP8 when WP9 is at the door.[/citation]
All systems, iPhone, Android and Windows have bad support in the long run. With Apple, it will be a new iOS version that makes your iPhone run slower, but without bringing most of the new features that the new iOS devices receive (besides a few security fix). And then I don't even mention the iOS6 fiasco... many people screamed to downgrade back to v5. It looks like the main reason Apple offers an update for previous gens iPhones is to defeat (temporarily) the jailbreaks that are in place and align the devices with their new "policies".
Regarding Android, the long term support has been very variable depending on the manufacturer of your device and the specs of your phone. In lots of cases, your best chance for having an upgrade is to play with custom ROMs. But while I enjoyed testing all those ROMS as I am a tech junkie and finally found more or less what I was looking for, I have to admit that many are not that stable or miss features and the average consumers have nor the time, nor the competences to do this. The more time you spend customizing your ROM, the less you actually use what you paid for.
Most end-users don't know about upgrading their phones and don't event want to know what's under the hood. They use it as it ships out of the box and install the apps they need. As long as they find the apps they need for their devices and that the devices run smoothly with them installed, they don't develop negative feelings towards the OS of their device.