I'll admit to having not read this thread because I'm just going to give my reasons rather than debate other people's.

When I buy a phone/smartphone I want to pay for it and own it free and clear. Nokia gives me that option while others do not.

It's not purely about whether the operating system is "open source" or not but how open the services on it are and how open the access for application delivery is.

With Android you're entirely dependent on google for services and application delivery. You're essentially paying twice for the device, once to the manufacturer and again to google via generated ad revenue to actually use the phone. You can't use their maps offline nor will you ever be able to. All of their services are geared towards online service access because that's what google are about.

With Nokia you can generally install applications from anyone even on Symbian. You're not restricted to a controlled application delivery mechanism which has been demonstrated to not always be in the interests of the consumer (in Apple's case at least). With Maemo in particular it's a much more open platform in all ways.

So if I'm going to pay €500 for a phone I want to buy everything that comes with it. I don't want to pay just so I can be monetised as ad revenue statistic.