I suppose that it's really a matter of preference (as mentioned towards the end), because I personally dislike the way, for example, some PNG files might open in Preview or possibly Photoshop if I created them with PS.
Recent case in point: I received HTML files from a designer that opened in Dreamweaver because that's what she used, but I really just wanted to open it in Safari. (I never use Dreamweaver)
"matter of preference" == "a case for configurability"
Personally, I'm with you. I like the simplicity of the one-app-per-extension model. When I want to edit something, it's easy enough to open it in TextMate.
I guess it would be nice if files kept track of individual users' preferences. In fact, I wish Finder would do the same on network shares; I hate opening a network folder and realizing that one of my coworkers has changed the way things are organized.
But that seems like the kind of tiny feature that's a lot of work for not a lot of reward.
Doesn't seem like it would be a lot of work. Just tell Finder to ignore folder/file-specific settings when accessing files/folders on a network share. That way all preferences just go to your defaults, though you also can't change the preferences and 'make then stick' it might be a compromise solution.
Recent case in point: I received HTML files from a designer that opened in Dreamweaver because that's what she used, but I really just wanted to open it in Safari. (I never use Dreamweaver)