When people ask me if WP has this app or that app, many times I say yes but other times I say "No BUT there's a really good alternatives that work well such as..." I think some people don't consider 3rd party apps any better than the original per say, either that or they might have a bad experience with 3rd party apps on whatever platform they use. Either way when I say 3rd party or alternative, most assume it's a bad thing. I even explain how most of the developers of these apps work hard and support their apps better, etc and even then its hard to convince them sometimes.
If Google plays "hard to get" for WP then that WOULD scare away potential buyers even if there are alternatives 1000x better. Just look at the effect it has for not having the "official" Instagram app, etc. Microsoft is doing everything they can to get bigname apps and we see that almost every day with big name releases. Even then, it takes time to get Big name apps on board, for development, release, certification, etc.
Google can't grow for ever. Their growth will slow down at some point. WP is still young and has room and potential for some serious growth. That along with the tight integration with other MS products should hit a home run.