I think what is wrong with ground handling is that as the plane goes faster, same as with fast cars, the un-eveness of the road is less noticeable because at high speed the wheel's shock absorbers are absorbing most of the impact of the tire with bumbs on the road... so same should be with aircraft on take-off and landing. When slow the plane should be wobling noticably, but as speed increases (I think 100Km and more) the wobling should be reduced.
Most of you drive cars... pay attention as you drive really slow... you will fee every bump on the road, even if the road seems perfectly straight and even... but as soon as you pick up some speed, the car is driving much calmer.
So in short, very small bumps (like parts on runways where conrete blocks join) should hardly be felt at high speed, but large very gradual un-even surface is more felt at high speed (that's because the impact frequency of the bump is very high for small bumps and very high for large gradual "bumps" - think of the runway as very long wavelength looking surface)
I can't really put the right words how to describe this :(