Frank at Overly Positive has written a rather scathing post about The Silly Subscriber Number Worship.
Aiiane at Up Past Midnight also feels too much weight is given to subscriber numbers. Syncaine crows about Aion struggling while explaining how in his view subscriber numbers mould the games that get produced.
I think subscriber numbers are a reasonable indication of a good game.
Of course there are niches and one has to respect that a full loot pvp game or a permadeath mode only game are unlikely to get high numbers since they appeal to a small subset of the gaming public.
Still I think in general that the audience is discerning and good at filtering out what it likes from what it doesn't like.
The McDonalds analogy is flawed. There are genuine medical reasons why living on McDonalds food is bad; there are environmentalist issues arising from the company's ranching practices in the Amazon Basin, there are aesthetic issues regarding the look of high streets and there are social justice issues around low pay. So many people dislike McDonalds for reasons that aren't related to the product.
Subscriber numbers point to WoW being a better game than Warhammer, once seen as a potential "WoW-killer". Looking more specifically at that subset of the WoW-playing population who cancelled their WoW subs and bought Warhammer one sees that the majority went back to WoW. These are people capable of making choices about what they like. To assume they are all sheep or stupid or tourists is to denigrate them.
One can further analyse the game mechanics to see specific reasons why WAR failed to retain high numbers of players. It's a mass pvp game and didn't function very well. Keeps were takeable using weak points. RvR generally does not work well with two realms. You get the everyone joins the winning side bandwagon effect.
Next just as the presence of an observer distorts an experiment the mass of subscribers or lack of subscribers distorts the numbers. Most people want to play a game with tons of other people. It's sensible - why grind to level 80 in a game which only has 10k players and thus might get closed down by the time you max out?
My main caveat is that companies distort their numbers. WoW for instance counts every unopened gamecard they've ever sold as a "current subscriber" and counts people who pay 5 cents to play an hour in a Chinese cybercafe once as "current subscribers".
In any event now that WoW has lost the rights to operate in China it's unlikely we will ever see WoW numbers released voluntarily again. (People may be able to deduce numbers from company financial information they are legally required to submit). Most people think WoW has 11 million subscribers, in fact they may well have less that a million active subscriptions.
Some marketing people even scroll through all their available stats before dredging up some number that sounds good. Champions Online recently announced one million characters have been made in the character creator. What the hell does that have to do with anything? They may have ten thousand players. Or less. By all accounts the character creator is the best thing about the game so it's hardly surprising people are playing with it.
What's even more astonishing is that a number of bloggers and games journalists have divided it by four to suggest that Champions Online has 250K subscribers. Huh? Sorry guys if you take a figure that means nothing and divide it by four you still have a figure that means nothing, not a point of information.
It seems to me that if the only stat you care to reveal about your new game is something completely out of left field like people playing with the character generator your real stats must be shockingly bad. If CO actually had 250K subscribers they would be telling everyone. It's like claiming your game is a success because the /dance emote has been used a million times.
In conclusion once one gets past the deceptive methods generally behind any figure you get a ball park idea of which games are doing well. A game that is doing well is generally doing well because people enjoy playing it which may be a sign that you too would enjoy playing it if it's your style of game. Further a game with good numbers is protected from some of the calamities that strike games that are financially challenged: lack of extra new content, failure of game elements that require massive participation to work, lack of people to group with and so on.