That more MD teams have not advanced in the NCAA's is a recent trend. It would have been unheard of to see a school like Denver or ND in the NCAA's 15-20 years ago. Lacrosse of any significance was basically restricted to Long Island and the Mid-Atlantic.
I too grew up in Baltimore and never played an inning of little league baseball since it competed with lacrosse season in the spring. Lacrosse rivals football for the biggest HS sport overall in the area. Just look at any college roster and you'll see pretty good representation from Baltimore/DC high schools.
With more colleges in play, more local talent is leaving the state for other programs like ND...also there is a ton more talent being produced from other regions of the country as it gets more popular.
I read an article within the last couple years that said something to the effect that half or more of the high school girls lacrosse players in Anne Arundel County went on to play in college.