It's not like grouped icons wasn't technically infeasible on win95. And honestly, whatever they are more useful is quite debatable. And personally, I don't even have a task panel anymore.

The real stuff not on Win95 that everyone would miss is scalable interfaces/high DPI (not necessary as in HiDPI, just above 640x480). And this one does require A LOT of resources and is still wobbly.

I'm not sure what you mean by "Technically feasible", but it wasn't supported by explorer.

You could have multiple windows, and you could have MDI windows, but you couldn't have shared task bar icons that expand on hover to let you choose which one to go to.

If you mean that someone could write a replacement shell that did that, then maybe, but at that point it's no longer really windows 95.