The move makes sense from a competitive standpoint; with the league schedule expanding but the competition window squeezed, shoehorning in SuperLiga would stretch participating teams in truly adverse ways. MLS has continually stated that it wants to reduce the strain on clubs. Playing SuperLiga after all that talk would come off as hypocritical.
But like Davis, I think there is something to be lost here, a chance to regularly compete against Mexican sides, considered to be, and usually are, the best clubs in CONCACAF. But ending SuperLiga is not giving up on the dream of competing against the region's best clubs and winning; it is a realization that there is probably a better way to do it. For example, by taking the CONCACAF Champions League more seriously at the league level and giving teams the proper tools to have a shot at winning. It is also the more mature understanding that success in this game cannot be bought with a dream, but will come only with time and work.
Sometimes it is important to think of MLS as the teenager it is. Look at any 11- or 12-year-old kid (the age of MLS when the SuperLiga started in 2007) and you will find hopes and dreams--often beyond the immediate or even short term reach of that kid. That is not to say that the 12-year-old won't turn into a world famous footballer, surgeon, actor, astronaut or the President of the United States, but that kid must develop the proper foundation.
SuperLiga was the the MLS' equivalent of a kid's dream--ambition uncoupled from the reality of MLS' actual capabilities at that time and even now. With the MLS, Don Garber and the league leadership needs to build the foundation as well. Having the goal and ambition to dominate the region's football is admirable and laudable--as a long term goal. Right now, we have to build for the future by focusing on the foundation in the present.
MLS is really taking those important foundational steps. The academies and youth teams for the clubs which are developing home grown talent, the improved financial footing, the infrastucture in stadium deals and training facilities, better coaching, and cultivating a fan base by being true to the game and not trying (too much) to insult the intelligence of the fans; these are all positive steps that the league is taking to improve the domestic competition. MLS is getting better and that is where the proper focus needs to be. Success at the international level will come with time, patience and work. In other words, let the teenager grown, provide it the skills, the resources and the experience to give it the chance to excel and reach its dreams. If the league focuses on its own competition, international success will surely follow. The demise of the SuperLiga isn't so much a giving up on a dream as it is a reflection of the maturation of a teenager who realized that having dreams is good, but like all good things, you have to sometimes accept that achieving the dream takes time and hard work.
The SuperLiga may have been a contrived, poorly constructed money-maker for the league. But you can't fault the teenager for dreaming big.