It's not a bad idea. The old Mac OS had something like that and
Windows has a similar facility now as well. But I never liked it very
much because it always seemed to get in the way more than it helped.
For instance I might want to open an HTML file with Word, then open it
with Notepad, then open it with IE. As it stands now, I have to set
up the file type to be associated with all three (and other
applications, if I want them), then right click and navigate through
the context menu to select the right application. That sucks. It's
easier just to have a console open and type "notepad mydoc.html".
It's less stressful. Maybe there's some way of getting around those
problems (the need for setup and the difficulty in constantly
switching from one application to another).