1) MAPS

I think you are missinterpreting. Maemo5 has maps 1.0 that are not the same as the maps 2.0 on symbian. For symbian maps 3.0 are beeing worked on.

You might be confusing versions over here because maps 1.0 on N900 is pretty much what maps 3.0 on symbian is going to look like.

And even if it was so grim (current Maps app is not so bad IMO) as you describe, the Maps application is just a viewer, it doesn't matter what version you have, you'll always be able to get the latest maps made by naviteq.


2) Stores and repositories

Android only shows you apps compatible for your current phone since compatibility is greatly broken between devices and android distributions, on maemo you can choose to see apps from OS2008 if you're a developer.
OS2008 partly preserves compatibility, but nokia wants Maemo5 apps to keep to the new "hildon" user interface = look cute, so that's why the repo's aren't merged and many 2008 apps are in extras-devel or testing already.
Also apps running on Maemo5 most probably won't run out of the box on OS2008.

IMHO this is far batter than 3GS games that are still forced to have 3G-like graphics for compatibility's sake.

So in the end you have the app-manager where you can centralize repo's for independent developers that create free apps eg. the repos from this site, repos from paid developers that don't want to go through OVI and prefer other payment methods, all looking like a single app store.
And the OVI store that can also be centralized to the app manager but also viewed from the web.

For winmo there never was one market alone, there's plenty of sources for plenty of distributions and the best source for winmo apps is google.
Android and apple are quite new to the market and it wasn't hard for them to say: all apps go through here.
But even so many android and iphone apps are rejected from the stores for various policy aspects.
Try scooping those out, it's just the nightmare that controlled repo separation prevents...

With maemo it all gets centralized via a repository in the app manager. Developers have more freedom and don't have to lick boot to be allowed in the "store" and we can have all applications in one place by adding an URL.

Conclusion:
It's easier to centralize more download sources into a specific device via an app-manager than force all the developers to follow the same protocol and move all the apps in a "central" store (if you know comunism, you know what those are).

Hope I made it a bit clearer