I agree with you, that DIYers and sole-proprietors often need the Pro Solid Tools and LayOut.
I also just re-requested this same idea as a “Craftsman” license. Ie, more than a hobby, but less than commercial company. My idea is that (like the Make license,) it is restricted in what or how much you can use it for.
The main idea is to get more crafters helping to fund SketchUp improvements, which may also allow the Pro price to drop back down to 499+99yr.