Like most people here, I too hate that we’re required to have Silverlight install, just because of Netflix. As is “best practice”, I run with as few plugins as possible, as each one represents a real or potential security hole. (You can physically remove plugins by looking here: ‘/Library/Internet Plugins/’ and here: ‘/Users/YourUsername/Library/Internet Plugins/’). Netflix chose Silverlight because at the time it was the only cross-platform codec that supported DRM at the time. (And, as you can guess, DRM was required by the movie studios so that Netflix didn’t turn into a movie-downloading site).
Speaking objectively, Silverlight does have some really nice features that are unmatched by Flash or Quicktime. Namely, not only the ability to throttle down due to bandwidth congestion, but more importantly the ability to throttle back up as congestion loosens. I also like Silverlights way of handling scrubbing thru a movie.
And, as others have pointed out, it looks like Microsoft has depreciated Silverlight in favor of supporting the industry-adopted h.264. This, of course, is a good thing. Hopefully those Silverlight-developed features will be rolled into the next version of h.264 (h.265?).
Yes, it sucks that we have to have Silverlight installed for essentially the one website on the entire planet that uses it. But, as far as the plugin itself is concerned, it’s not all that bad. It doesn’t suck down your machine like Flash does, for example.