The only area Google has really killed in is search, PPC and maybe a couple of other things. Everything else ranges from pretty good to horrible (but not killer.) Personally, I use Gmail more than any other Google service but I bet Gmail doesn't have the same dominance as their search does.

My opinion is certainly debatable, but the point is that Google does not automatically dominate every area they get into and some of their services are terrible.

Also, I am pretty sure Microsoft has tried the "whole army" thing with search and look at where that has got them.