I refuse to install it because I haven't been convinced by people that I trust that there's anything that demands Silverlight. There's enough quality content that uses Flash that it's inescapable.
I'm not against installing Microsoft products on my system; I just upgraded the WMV codecs from Flip4Mac (now owned by Microsoft) last night. I've got Mac:Office. I'm just not interested in installing an inessential plug-in for something that I'm going to visit just once and probably never play with again.
You also didn't address the point that Silverlight just isn't cross-platform enough. Flash cross-platform support sucks (I can use it on Linux), but Silverlight cross-platform is nonexistent (as "Moonlight" is still essentially a Silverlight v1 implementation).
Wow .. you refuse to install it because .. why ? It's MS ? it's a small plugin man get over it.
I constantly see this : ohhhh it's silverlight, nevermind what the application does - let's throw stones at it cause it's silverlight.