The new Android version "4.3" has very little noticeable changes. Not every update is going to be earth shattering, just saying.
I'm not sure that is a fair way to look at it. Instead, I bought a Nexus phone 13 months ago. When I first bought it, it had Ice Cream Sandwich on it, version 4.0.4. Since that time, I've had upgrades to 4.1, 4.1.1, 4.1.2, 4.2, 4.2.1, 4.2.2, and now 4.3. This is also despite the rumors of a huge update (5.0) that is in the works; it was originally "expected" last October/November and is now expected this coming October. So while 4.3 may have been an update that has few changes users see, it is merely one of several updates over the last year -- with a major upgrade having occurred about a year ago (Ice Cream Sandwich to Jellybean) and a second major upgrade expected by the end of the year. And even if 5.0 isn't released by November, it is a solid bet (based on history) that they will have enough updates/improvements to roll out a 4.4 update.
As for many Android phones not getting all the updates, I'm not sure we can compare that to WP, at least yet. I know on the Lumia 810 forum they are scared of their phones not being updated, since it is already EOL. I'm guessing they will get updates, even if delayed, but I think it does point to it possibly becoming a real issue in the future. There are currently hundreds of Android phones on the market, and there seem to be signs that if WP ever becomes that popular that manufacturers/carriers will quit providing timely updates (or any updates) to EOL and less popular phones. And Android at least has the advantage that you can root your phone and develop/install your own updates if no updates are officially available.
My fear is based on Microsoft's past, they have a very bad track record when it comes to mobile products. They get in, they play a couple of years, find that they are having trouble making a profit, and they get out. I'm afraid Microsoft is trying to evaluate where they are with their mobile products. While I don't believe they are ready to give up, my fear is that we are seeing the mobile side become less of a priority.