The futuristic science fiction super armor wearing super soldier? 

I guess it sells with their core base so they should stick with it. But its lack of diversity in main protaganists really hurts it's appeal to me. 

However Alan Wake is on the horizon!

Hopefully it starts a trend of appealing characters that are not just recycled parts of what they already have. 

Well, technically MS isn't really developing any of them (if you are thinking Gears and Halo). Just helping publish and promote - 2nd party, maybe. The stuff MS themselves have really tried to get going from the ground up is anything BUT the super soldiers, because they know that expansion is limited if you only make shooters.

It's not like they haven't tried other things - pinatas anyone? (Yes, please.) they just haven't been bought because the soldiers came first and that's the dominant user at the moment.

same reason nintendo loves mario. he sells.

Last time I checked...publishers make game that sell...the question isn't why M$ is in love, it's why consumers are in love, since we are the ones who decide...

The original futuristic science fiction super armor wearing super soldier:

I didn't necessarily mean they have too many shooters. And I understand they are going away from the shooter genre much more now than initially. What I meant more was when they do have a game that involves shooting it seems they use the same type of protagonist in the same type of world.

Well regardless of whether they were developing or just publishing the games they did have a big say in the development process. Maybe it is their strategy, and a good strategy at that. They know what their core likes and they keep pumping out games that that core will keep buying. Obviously to grow and expand they have to diversify but now they are locked with major franchises that use this type of protagonist.

Yes Publishers make games that sell. However first and foremost Microsoft is a video game console manufacturer. Their main goal is to expand the userbase. Not that it is not expanding (price cuts and such have worked great), but there is more to publishing games when you are the console maker than just selling games. 

its a testosterone filled armor plated big guns shooter world :)

With Alan Wake peeking his head in and saying "well, you know writers are cool too...hello?...oh come on....you loved my game, now love us too!"