but again these corporations don't work like this.
What's crazy is that "good" corporations CAN work like this. Big companies have smaller, yet profitable, sub divisions all the time. Are they big bucks? Meh, they might be 10-25% of total revenue. But they can have all kinds of synergies that you might not expect:
1. Increase market share to niche markets. The hardcore market is niche. and having something like a vanilla server would probably be considered hardcore. But what you accomplish is more and more people buying Blizzard products. It's a way to grow influence, even among the hardcore. It's similar to what Larian is doing, but on a broader scale since Larian has one or two main products. But the point is that they can walk the line between being hardcore and accessible. And they don't get killed for it.
Anyhow, more people buying your products creates buzz and goodwill for a company. Think about it, who are usually the most negative voices on the internet? The hardcore. Get an executive to form a team that understands that market well, and you can kill a lot of negative publicity by just catering to that crowd in a low budget and profitable way.
2. Extend the life of related products. Look, if you are getting tired of the current content of WoW, something like a vanilla server can keep you occupied enough until you've been away to come back to the main content and buy expansions. What's the alternative? Subscribers start saying "fuck it", get burnt out, and quit. It happens all the time. The beauty of vanilla servers is that it serves as a "holding pattern" of sorts for people who get fed up with some of the streamlined options or who outpace all the new content.
3. Bring in lost money to the company. What was Nost's population? Like 200k? I mean how much money is that if 80% are subscribers? How much is that if they buy expansions in the future? How many of those would pay for an HD upgrade to the vanilla game?
4. Ride the momentum. Right now we are living in a nostalgia wave where old and forgotten IPs, mechanics, and all sorts of ways to enjoy content (rela manuals anyone?) are experiencing a revival. Much like it's easier to use a broken path by sled dogs versus creating one yourself, it's much easier to jump on the bandwagon than to start it yourself. Appealing to nostalgia, at this point in time in video games, is slightly a bit harder than shooting fish in a barrel. A few years ago? Shit was way too easy if you were well organized enough and had some money. Now some bad projects have left a bit of a bad taste in the mouth for the nostalgia-driven (Realms of Arkania HD remake and HoMM 7). But the money pot is still there, for companies who are willing to put on their late 90s/early 2000s caps on.
EDIT: Last thing I'll say is this...Steam and itunes have proven that if you make things easy, relatively cheap and accessible for people who normally pirate things, then a large majority of those people will instead choose to just go ahead and buy the product. Just like buying a game with patch support on steam is sometimes better than pirating a buggy and unpatched copy, a vanilla server run by an ACTUAL team of dedicated professionals is going to be really attractive to a lot of the people who play on Nost, rebirth, or whatever.