From what I can see, the reason is simple. WarCraft III DotA has millions of players. It STILL HAS millions of players, even though there are maps like SotIS out there. And a large percentage of those millions of people have pirated WC3 to play it. Also, games like Heroes of Newerth and League of Legends have attracted more millions, many of them ex-DotA players. What Blizzard is doing is trying to get a piece of the pie. StarCraft II online requires a legit client, so it's very difficult to have something like garena where you can play pirated copies of SC2 on. Therefore, playing SC2 DotA requires you to pay your $60 to Blizzard. Let's say 500,000 people move from LoL/HoN/WC3DotA to SC2 DotA. Maybe it's only a tenth of the community, or less. But that's still $30,000,000 dollars, which is easily worth the thousands they spend on game designers and artists and a month or ten of balancing. And think, if they release the next two installments of SC2 and update DotA to be only playable on those versions, there's another $120 in their pocket by all the people playing DotA.
This also means that Blizzard is happy for SotIS, TS, Hero arena, and all the other AoS maps to be popular, because they also attract users from LoL/HoN/WC3DotA, who also pay their $60. They're just using their copyright of the DotA name and their abilities as a game design company to make a superior product to attract more users, which it would be hard for SotIS/TS/heroarena/over9000AoS's to compete with, but is competitive with LoL/HoN/valve'sDOTA/WC3DOTA. And this is also why DotA won't be released tomorrow; they'll want to make sure it makes a big market splash, so they'll make it balanced, bug-free, and competitive before they release, which takes time.
I suppose the final question is Will It Work? Will people pay $60 to play SC2 DotA when they could play WC3 DotApirated/LoLforfree/HoNfor$15? That's the real question, and I think Blizzard's too late. Maybe some people will, but the majority of people who play SC2 DotA will have already bought SC2. We'll see though. Should be interesting to see how things progress.
Red classic.
"In short, their absurdities are so extreme that it is painful even to quote them."
"In short, their absurdities are so extreme that it is painful even to quote them."