The Point Is This
The point is that there are a lot of .Net developers out there that would love to be able to develop really good looking and interactive web apps and without Silverlight there is no easy way for them to do that without having to learn to code in Flash etc. Silverlight allows these developers to use their already existing skills and as a bonus to Microsoft it keeps them tied in to using Microsoft tools etc.
From a user persepctive it will hopefully lead to some decent web sites / apps that look great and have tons of functionality. Installing it is a no brainer for most users (those using windows and IE).
Yes it would be nice if we all used standards that meant anything and everything could be viewed no matter what platform you were using but I suspect world peace and a end to all hunger will arrive long before then. Personally I like a multiplicity of choices, life would be boring if we all did the same thing.