Why render animated graphics in xMII and not in browser?

Hello,

I'm doing my first steps in xMII and try to create some animated graphics. I had problems with rendering pixel graphics inside xMII, see

This gives rise to the following general question:

Is it necessary to create a pixel graphic for the browser? If yes, what are the reasons? Why don't we simply embed the (modified) svg file in the result page? (using iframe, embed, or something like that...)

Kind Regards, Matthias