Heh. Well, I can't speak for Firefox, since I don't use it (I dislike the idea of plugins, I'd rather have functionality built in...) However, AFAIK IE doesn't handle XML properly either... not according to spec, anyway.
(I have to admit that your desktop/program files problem baffles me a bit. Erm, don't pretty much *all* Windows programs install to Program Files and create shortcuts? About the only ones that don't are the (unfortunately) very rare self-contained ones.)
I will say that in the case of your plugins, however, it's the fault of the people who make crappy plugins, not the fault of the browser. Which brings me to...
As for why people would want to use Flash, it's great when used for what it should be used for, stuff like games, movies, and interfaces that can't be done with basic (X)HTML and DOM stuff.
Ditto for javascript, it's great when used to enhance web functionality in ways that basic (X)HTML can't do.
In short, don't fault the usefulness of a technology because people abuse it in stupid ways.
Peace & Luv, Liz
P.S. I personally bash IE because everything it does there are other browsers that do better and with IMHO fewer problems.
Furthermore those other browsers do helpful things IE doesn't.
Even furthermore, since IE doesn't follow standards and uses lots of proprietary stuff, there are so many shortsighted webmasters out there who blindly code only for IE, and it interferes with those of us who want to be able to choose which browser we use.