I don't know if the LA Galaxy got the "return" on
their huge financial investment, but the league definitely did.
For the 2006 season, MLS had 12 teams, five soccer specific stadiums, and a league average attendance of 15,504 fans per game.
For the current 2012 season, MLS has 19 teams, twelve soccer specific stadiums, and a league average attendance of 18,807 fans per game.
Of the teams in 2012 that do not have soccer specific stadiums, one could argue that Portland's Jen-Weld Field is soccer specific, since it is a converted AAA ballpark (baseball no longer played there), Vancouver's BC Place Stadium is a conversion as well (the Tulsa Roughnecks played Soccer Bowl '83 at that stadium in its first year of existence), and Seattle's NFL-sized CenturyLink Field was built with MLS in mind. This leaves only teams in DC and New England playing in older NFL facilities, while the San Jose Earthquakes are playing at tiny Buck Shaw Stadium until its new soccer specific stadium opens in 2014
http://www.sjearthquakes.com/newstadium