It is clear that SVG should not support scripts and CSS in SVG files. Those who need them can simply create HTML with inline SVG tags and scripts. And SVG should contain only shapes, effects and transformations.
Or maybe we need a new image format, "SVG without scripts and CSS".
CSS and scripts are wildly different. It's like responding to the old MS Office attacks with "Word without macros or font selection"
The problem with CSS is that if you want to write an SVG viewer, you have to implement a whole CSS engine, which might be more complex than SVG renderer itself. And if you create an image in an editor, like Inkscape, you don't use CSS anyway. CSS is meant to be used when you write the code manually (instead of using an editor), for example, in a web app, and in this case you could use HTML as well.
So yes, CSS is not needed.