I agree, except that I don't have any sentimental attachment toward Nokia like you do.
It's something more than technical difficulty.
The reason why iOS or Android couldn't find an app in their appstore that could play more formats than they're supposed to be is the royalty and licensing issues with some codecs.
For example, mobile manufacturers must pay SUN the royalty for every devices sold that included SUN's JVM. That's why not all mobile devices could be able to run Java even it's technically feasible. Distribution of media codecs is even more legally complicated in this case, and the legality is varying for different regions. Of course you'd then say Android could do the job with some hacking, but IMHO N900/Maemo can do better, and easier job in this case. You may start the debate on abusing freedom on copyright, licensing and royalty, but I'm not going to argue as it's my believe that some of the legal issues are abusive on themselves. I know you are well aware of above but for some reason they didn't come to your mind when you stated your arguement. So please regard it a friendly reminder for you. Hope no damage is done.