While MLS does compete with football at the end of its season, the majority of the season is played during the summer, thus only pitting its clubs against baseball for attendance. A larger than normal share of MLS's profit still comes from attendance, rather than TV contracts, unlike NFL, NBA etc.
Take Sporting Kansas City for example. Would SKC rather compete against the Chiefs or the Royals for an average KC sports fans' weekend money? It's far easier to sway people away from one of 81 home baseball games, than one of 8 home NFL games. Why sacrifice half of your gate receipts for a more European schedule?
I do think MLS stupidly schedules MLS Cup on the weekend rather than in the middle of the week when there's less competition for sports viewing.
There's more in this argument, but that's the basic idea.
This post was edited on 11/30 at 5:13 pm