They lost one, Kroenke wanted to make the Rams an international brand, but St Louis blocked him from doing additional games overseas. Given his pitching videos for the owners were heavy on international fans visiting the team, that obviously played a role in his pursuit for LA.
Anyway, you're still looking at the 10 game thing wrong. Would 10 be better? Sure, so would 11 games, but I don't see people saying that the fans are getting ripped off for it not having 18 games per season. The NHL has 41 home games, is it fair they get so many more games than the NFL? That's not how it works.
Again, 10 isn't an option. Imagine Mark has 10 apples. Bob has zero apples, and would like an apple. Tom asks Mark if he can have the 10 apples to give to Bob. Mark says okay, but only if one apple goes to Dan. So Mark gives 9 apples to Tom, who gives them to Bob, and 1 apple to Dan.
Tom (Kroenke/Rams/whoever) doesn't have 10 apples to give to Bob. He has 9. Mark (the NFL) has already decided to give an apple to Dan (London/China).
If you really care about the fans, and aren't just looking for an excuse to further label Kroenke as a piece of crap, then be mad at the NFL. They're the ones who gave away that 10th apple.