I dunno, 30 kph is pretty reasonable, very close to the US 20 mph max speed, and much better than the UK's 15 mph max speed.
Most of us are riding modded MTB's, so to me, riding at or close to 30 kph, with only moderate pedal assist, is reasonably satisfying.
If you need a reality check, then its just amatter of riding a normal MTB, and see what speeds you get! Makes really appreciate even modest levels of power assist. i.e. when I'm riding against a strong headwind, I would struggle to get to 15 kph, and that would be with a lot of effort, add power and I can easily see 22 kph, or more. Makes a huge difference in the commute to work.
even on my road bike, Idon't think I'd do any better against a headwind.
I like what I can get out of 250 watts!
However, I would fully support an electric moped class of vehicle, but I don't think the legislators woyld support that this clas of vehicle would be bicycle based, more purpose built, upgraded brakes, indicators, speedo, mirrors, mudguards, safety cut outs etc. etc.
Rob