The app catalog isn't the issue at all. Like any other smartphone, you can go into a market and download apps. But being a smartphone, there should be alot more room to customize and organize the user interface. Also there are very limited settings for general phone use. Wp7 almost feels like a demo version.. You get to use the metro UI and you have a list of apps, but when you delve deeper into settings, you can't do much else.
I am not knocking this phone, just trying to state why people may not wanna convert to it.
As far as the settings go, you can change many of the aspects of the phone, and what you can do is very comparable to iOS. It seems to me that you favor android because of its customization, and you are right, windows phone 7 does have limited customization, but its every bit as limited as iOS. I will say that personally I am not an apple user, I don't use OSX, but one thing I feel that apple does right is that they don't let people customize iOS very much. I mean you can arrange around your icons, you can put stuff in folders, and it definitely has the best app selection, but with the setting its not as robust as android. If there is anything I have learned about people, Its that when they get access to a lot of in depth settings, most of them somehow screw it up. I work in a computer store, and people come in all the time when they did something like, disabled the wireless card by hitting a button on the keyboard or a switch, and a lot of people come in when they hit a button and turn off the mouse pad and can't figure out how to turn the mousepad or wireless card back on. stupid stuff, you might feel that this is obvious to you, but most people in general don't want to have to always be tweaking and trying to get there phone to work, they want a phone that just works well without them having to worry about it.
That's my main gripe with android, it is the freest OS to use, but its open source hurts it too. For example, the quality control from brand to brand greatly varies, not only that every android brand also works differently. Samsung touchwiz, HTC has sense, LG has their own, so does sony, etc. And the user experiences vary greatly from phone to phone, and in my personal experience, I don't think now that there is a single android skin that actually improves the user experience over stock android. If I were to buy and android phone today, the only phones I would even consider would be the nexus line because they are some of the only ones with stock android, or I would root the phone.
The thing I like more about wp7 is that it doesn't matter if you get a high end phone or a low end phone, since all wp7 phones use the same single core 1.4 GHz processor, all their user experiences are exactly the same, save for the features you get with different phones (like form factor, screen size, thin-ness, etc.) You can't say that a 50$ android phone runs like a 200$ android phone.
My other gripe with google is I feel that they have a poor sense for ui design compared to apple and M$. For example, itunes on iOS looks and feels like i tunes on the computer, which is like safari, and lion, and apple tv, and the ipad, and the iphone etc... WP7 metro is like the xbox, and soon to be windows 8, the uis on both companies are very consistent from device to device. Also when both companies change the look of things, they usually add significant improvements, google, i feel, will just change the look of things because it feels like it on a whim. I mean take the new youtube and gmail, was their any need to change it, I don't feel that it even looks more cohesive than it used to be and I don't feel they really added much functionality. When Honeycomb first came out, I had to re learn another OS that was very different the standard android: for example, how come android has four buttons on the bottom: home, back, search, options, and the notifications bar is at the top and the apps launcher is looks like a grid on the bottom.
On honey comb, there are no hardware buttons, there is a bar at the bottom that is home, app switcher, and back buttons, search is on a bar at the top left of the screen and apps are in the corner at the top right of the screen? and the notifications bar moved to the bottom? I know they are changing this with ice cream sandwich a little, that they are removing the hardware butons at the bottom, but the apps button is still located at the bottom and the notifications are still at he top, it seems that its inconsistent with itself. I'm not saying that apple and microsoft don't have a habit of doing stuff like this too, but I feel that they are much more consistent and sensible with their decisions compared to google.