Nothing wrong with soccer. It is a good sport. However, there are many other competing team sports. So, professional soccer is competing with all them for fans, The NASL created a lot interest in the 70/80s when they recruited the top international players. I suppose they would have to do that again to “kick-start” professional soccer again in the US.
One of the best documentaries I’ve ever seen (it’s on Netflix), is called “Once In a Lifetime” the story of the New York Cosmos.
The problem with the NASL was that other teams couldn’t keep up with the Cosmos, and eventually it all fell apart.
I don’t see soccer as very much of a “team” sport. The players are on sides, but they are not really teams. Co-operation among players on the same side seems to be ad hoc and there is no strategy.