I would disagree- I ride newer lighter weight cruisers and I haven't had any problems . Of course, my bikes are a large part of my TRANSPORTATION, so I treat them with respect, and never thrash them.
I think it helps though to think of bikes more as the sum of their components- because once you get into the motorized bicycle scene, you'll probably want to change stuff around anyway.
To me cycling has always been very simple and I base it on one principle- How to get from point A to Point B with the least effort.
You can tell I'm not a custom builder- and I don't try to make the motorized bicycle look or behave like a motorcycle. I want a great roll and a light bike first of all. I still want a bike that pedals easily, even with the motor on.
the same principles that apply to a Less-Than-A-Horsepower cyclist apply very nicely to the small motors we are working with.
While bike racing has only gotten more extreme and exotic since I retired in 1984, I very much try to balance a practical working strength with the motors and gearing. It's worked very well, especially here in Florida where the roads are flat and smooth.