Because as usual under current laws the content owners hold all the cards. Dish will eventually have to relent. Dish may be able to survive without Disney, but eventually Fox, NBC and CBS will come up for renewal. Each holding a large number of channels hostage. In a few years Dish will go under without channels, or submit to the demands. The content owners are under no obligation to license their channels to Dish, they want to because Dish will pay them big bucks. But, if they feel Dish is costing them money with ad skipping, they will not budge. They know very well if they give into Dish they will have every provider with ad skipping technology to deal with, all they have to do is say if you want to license our channels you have to agree not to have ad skipping technology.
It is way too simple of a demand from the channel owners not to demand. But, like I said above, if they can get more money from Dish to compensate for the perceived loss in ad dollars, they may come to a deal allowing ad skipping with extra money from Dish.
Despite the news articles which are just referring to what Charlie said about using it as a negotiating tool, the networks still hold all the cards. The lawsuits are over the current contracts, one of CBS's arguments is that Dish negotiated in bad faith knowing that they were going to be skipping ads and renewed the CBS contract months before the release of the Hopper. Dish has not won any suit. The only thing that has happened is that the networks have been unable to prove permanent harm and get an injunction before trial. There will be trials and probably take years.
I do think that the networks are being greedy and charging way too much for their content, making monopolies out of exclusive sports deals with events happening in sometimes public venues (in some cases supported by tax payer dollars). But, the way the copyright law is now, the copyright owner is under no obligation to share their content with anyone they do not want to share it with.