Weather does play a part your right. I think KingKymco metioned cities as well. I've been lucky enough to live for extended periods in 3 wonderful yet very distinct cities.
Pittsburgh, PA has maybe a 5 month long riding season. It's got a good public transportation system of buses, subways, trains and even inclines! I have not lived there in a while (over 5 years) but I think it's a good city for maxi-scoots to thrive in. It's also a older city with narrow roads and limited areas to grow into. See my comments on increasing urbanization.
Charlotte, NC is a growing city that has embraced public transportation having recently spent millions on subway's and trolley's. It's got probably a 9 - 10 month riding season (when I lived there where only 2 ice storms in 10 years and winters were generally in the 50's or 10 C). It was a growing city in the early 90's which was built around several highways. Again, while you might be OK with a lower cc bike it's probably better to have a mid range powerplant to get you around quickly and safely.
Currently I live outside of Tampa, FL. It's a year round riding season but has no public transportation worth a damn. In fact, I think there are more parking lots in this city than actual cars. A bigger CC bike is pretty much a requirement here and your seeing a movement towards the 250's here in Tampa.
When I travel to Asia or the islands like Bermuda, you don't see little 50's putting down the road. You see the 125's and 250's. Because they serve the needs of the public better.
Just my 2 cents.