Your experience, decotriumph, that a nice road bike is a good motivator to do more riding, is something I tried to tell hundreds of people over the years...

So many people come into a bike shop thinking that a heavy or slow bike will be better because you get more exercise per mile - which is true, but because the bikes are heavy and slow, they are less fun and less rewarding to ride, and you are less likely to actually ride them. Usually I could explain this to people, but many had their heart set on doing crosstown commutes on 2.2" wide knobby tires, so there was not as much I could do. I am sure most of those intentionally slow bikes are hanging in a garage somewhere with the molding hairs still on the tires. (to be fair, probably half of all bikes sold never or seldom get ridden by the original owner)