Well I really couldn't care less since as I said I don't like cinemas. Although I checked anyway and guess what... my local cinema is already owned by a movie studio. Movie studios owning cinemas seems to work perfectly fine in other countries so I don't get why you yanks are so worried about it.
The reason is because they could just refuse movies from other studios and price dumping (A cinema has to pay about 50% of the ticket prices to the studio, which of couse doesn't happen if they own them) which could force any independent cinema quickly out of the market if the competition is only half as expensive. There's also the risk that when a studio has a sizable amount of cinemas, they simply don't sell to other cinemas anymore, which would effectively be a death sentence to any cinema not owned by a studio.
And like @KManX89 siad, only Disney and Warner Brothers are really in a position to do this, they would also be a giant problem for other studios or even oversea production companies. Imagine that they wouldn't want to show anything else but their own products in their cinemas, meaning not selling movies to other cinemas but also not buying from them, and you would be quickly left with just WB and Disney owning the whole industry without any chance for any competition to even start anything without any venues.
The difference between the US and other countries is that the US is creating most movies. No other country (except maybe India and Nigeria) could produce enough movies to be independent from outside sources for their movies and have several new movies every week. In other words, in other countries they couldn't possibly put the whole market under lockdown, but in the US, they can, and quite easily so.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454