If the MLS sticks around for a few more decades, so you can get long term fans and rivalries, it has a better chance of taking off. Better players would also help, as would having the US team in more meaningful conpetitions (say have yearly summer tournament with the best teams from Europe or South America: they bring weaker teams for experience, the US wins, everybodies happy).
Freddy Adu also need to move to a European club in order to develop into a great player. Unfortunately, however good he may be a youth level, he won't progress much further with the quality of the game in the States. It looks like he may be going to Tottenham Hotspurs in the UK, which may be a good thing although they have a record of wasting talent.
With the low scoring thing, I like the fact that a goal can come at any time and change the course of a match. For every goal, there's usually a fair few opportunities which are missed.
Ultimately, it's a cultural thing. I couldn't watch a Baseball, Hockey, Basketball or Football game without getting far more bored than a Soccer game.