It seems that many of us who are mostly or exclusively road cyclists have multiple bikes. But if we only do one kind of riding, why? What's the story? I figure there are three basic situations.
Some of us are Collectors - it may even be ones line of work. Acquisition may be so habitual that one may have two virtually identical bikes.
One may not be so dedicated to collecting per se, but through the years, refining ones choices, occasionally upgrading, or just getting something "fresh," they just accumulate. The bikes may be fairly similar, but each is distinct in some significant way - one has better wheels and a lighter frame, another is more comfortable, another is kind of beat up. It is essentially ad hoc and fairly haphazard, but (although there may be an odd folding bike or fixie in there) the collection is mostly an attempt to approximate the perfect road bike.
The third basic situation is where I find myself. Each bike is a distinct type, and not necessarily a road bike; in my situation touring, race, fixed, and cross (wide tire). I have an acquisitive streak and the potential to fall into the second category, but lack of space and a sudden urge to acquire real estate instead have checked that tendency.
It's a question of more or less, really. I imagine that for most who have multiple bikes there's some of each going on. The poll is intended for people with multiple bikes, but if you only have one or two, you can still play: why would you want to have multiple bikes?