It seems to me that Google should work really hard on having its apps be must-haves for most users, then use them as a lever to discourage undesirable behavior like replacing built-in functionality such as tethering with paid services.
Even as of 2.3 though some stock apps, e.g. the media player are a bit basic, so it's only overall better, not a point-by-point victory.
There's also the fact that Samsung could create "tablet" versions of apps without waiting for Google, manufacturers having to replace Google apps on non-phone devices, and ROMs going their own open source way.
You could also argue, in a game theory kind of way, that the potential for replacement has aided Android in general (and therefore Android users) even if any particular replacement has been negative.
More importantly, this is a replacement done by the user. Being able to customize your own OS is always (in principle) a benefit. I'm talking about things like AT&T hiding Google Navigation on some of its Android phones to encourage the use of its own paid navigation app.
However, I doubt you'll find much help from Google when it comes to tethering, given their recent history: http://en.wikipedia.org/wiki/Android_Market#Banned_applicati...
(The tethering apps were apparently later unbanned, but that at least gives you an idea of their current stance)