i think international soccer is very entertaining, if you really wanted to improve soccer in my opinion, you would need to get rid of some teams or lesser leagues, that way the over all level of talent would rise per team. The mls is horrible to me, you have very few top players and is not very open.
Also soccer is not very big in america because the talent level of people playing here is not very good, if you moved the top english leagues into us cities, soccer would be huge here, but its hard getting behind a team and sport that is not local, not on tv very much, and time difference