More rules aren't going to help, the current ones aren't enforced
They've spent millions over the years on studies and you pretty much summed up the results in one sentence.
The last time I checked, in Toronto the maximum age for riding a bicycle on a sidewalk was fourteen. I used to think it had something to do with wheel size.
A couple of weeks ago I was driving along Bloor and about to make a right turn. I notice a definitely not spring chicken riding her bike in the same direction and estimated that we would arrive at the side street at the same time. I gave her a beep of the horn as I slowed to avoid a collision. She snarled "I have the right of way." I snarled back "No you don't. You're over 14 so get off the sidewalk." She continued on the sidewalk.
One problem is that the sidewalk usage regulations are municipal laws and could change as you cross the dotted line on a map.
I can understand cyclists preferring the sidewalks but where are the pedestrians supposed to walk?
Skateboards, roller blades, pogo sticks etc, wherever they want.
Even my Goldwing would fit on a sidewalk but I doubt I would get away with it. Some time back there was a thread about the legality of walking a disabled bike on a sidewalk.
Continuing with the idiocy, I see joggers on the roads where there are good sidewalks, mobility scoots on the roads after the city spent millions cutting every curb at every corner so they could use the sidewalks. I've seen cops on their copcycles riding on the sidewalks.
Bicycle insurance could be covered by a rider on a homeowner policy just like a small fishing boat.