Funny enough, something very similar to this was the impetus for me starting Estately. Early on, we had a bunch of wild spatial queries that would let you even filter by distance to specific transit line stops: http://blog.estately.com/wp-content/uploads/2008/06/near_tra...
When we ran stats on what searches people were actually doing, we found that very few consumers actually used these kinds of filters. We found we had a small and passionate audience for specific geo features and a much larger audience for "great site to search for and learn about homes." It took me way to long to come to terms with this. We still have walkscore search and distance from a neighborhood, school or address search even though they are very little used.
Why wasn't it popular? My guess is it's 80% because the market was small and 20% because we didn't present them right.
The thing about real estate - especially in the current market - is there just are few enough homes for sale that meet your price / proximity to work / school / bedrooms criteria that most people want to just glance at all of them and rule them in or out. Additionally, most people start with a bunch of "rules," then they bend one, change their mind on another and finally compromise on the last one.
The typical home search starts so clean, but dissolves over time as you tour houses, learn more about what you do and don't like and find something that works.