MLS more interested in growing relationships with Mexico/South America, tbh.
Always rumblings about integrating more with Liga MX, and with all the South American players coming to the league also makes sense to continue to create ties with South America.
And to answer an earlier question, no MLS team has won CCL but they have made finals. Just have had massive struggles with Mexican teams, though last year was encouraging in terms of results and this year should also see improvements with teams like Atlanta fielding easily a top-Liga MX quality side