EUV is all about the laser. To create the small transistors of 4nm for example, either lithography or some other laser tech, you need to be able to shine a pure light on them of small enough wavelength. EUV is the smallest we can create thus far.
I suppose that the real issue is that EUV is the smallest we can focus thus far. Otherwise we'd be using harder X-rays from things like synchrotron light sources, no?
You want to impact the surface, not deep into the material like X-rays would penetrate, so you can't actually go too low in wavelength either.
Isn't that a significant research field? New semi-conducting crystals and materials which would be friendly to x-rays?