ratchet426 on 07 September 2015
Number one reason: no time-outs/regular stoppage of play to allow for TV commercials.
No joke.
Every other popular American sport has built-in breaks during regular gameplay so the networks can sell tons of advertising time. Soccer rarely stops (ex. injury on the field -oops pitch, I meant "pitch" 
) so no breaks = no advertising $$$$
I don't think low-scoring is that big of an issue. Hockey has some low-scoring games too, and that's still pretty popular in the US (again, lots of commercial breaks)
There is a ton of interest/atcivity at the youth sports level in the US (we even coined the term "Soccer Mom") but it just doesn't have the pro-level audience of the big 4 (Baseball, Basketball, Football, Hockey)
