Funny thing, I’ve heard exactly the opposite - that soccer fans who look down on MLS because it’s so American. Now, a lot of that was from the first decade of the league, with names like Kansas City Wiz and Dallas Burn, a countdown clock, running penalty kicks (which I love and think is a far superior way to do PKs), and some still exist: salary caps (which have been essential in promoting parity), single entity (essential for the survival of the league), and no promotion/relegation (that’s a whole thread in itself, but I think the league is far better without).
The shift in more European names also was the time period where the league actually started growing (it actually did ‘fold’ for about 24 hours in 2001 before the 3 owners left decided to give it one more go - and owned multiple teams for a while). Sporting Kansas City is one of the big success turnaround stories in all MLS - and has been a template for the originals to use to change their luck.
A lot of American European club fans seem to look down on MLS more than Europeans themselves, strangely enough. They don’t see the immense strides the league has taken even in 1 decade. They still call it a retirement league when the average age of the league is lower than any of the Big 4, and when MLS is selling players to Europe left, right, and center. MLS has become a place for the young South Americans (Miguel Almiron, Thiago Almada, Taty Castellanos,etc) to finish their development before going to Europe, or young Europeans who are out of favor at big clubs or who are at mid tier clubs or leagues to resurrect things (Jack Harrison, Riqui Puig, Hany Muktar, etc), or the development of young Americans who will go to Europe (Weston McKennie, Matt Turner, Tim Ream, Ricardo Pepi, etc).
But people only focus on the big names who are coming at the end of their careers - yet don’t listen to those players when they talk about how much more difficult the league is than most people think (Wayne Rooney just said then when talking about Messi coming over).
It’s a league that’s growing by leaps and bounds. It won’t be the Big 4 any time soon, but it’s far from what some still speak about it. I think it’s slowly turning the Americans who are fans of European clubs, which is a good start.