Dave thinks there might be a correlation between the number of trains into a station and its development pattern. I think there is a bit more to do with it than that including market and available zoning allowances. But I think sometimes the market can be influenced by the amount of transportation available to an area over time.
For example I believe downtown Oakland was a little hamstrung when BART decided to split off trains to Fremont before going through a downtown Oakland station. With four lines instead of two going through downtown Oakland, it seems like it could have changed Oakland's equasion. Currently there is high frequency in the morning and evening rush, but at other times it could really use more trains into and from San Francisco. When there are opportunities to provide more service to a major destination, it seems like more service is a wise move that might be able to set the table for other improvements.