I agree, definitely. There is no fine line behind success of a Wiki, other than that of the personal goal of the Wiki-creator.
Such goals could be as you listed, to have a certain number of pages, editors, active members or anything. Success of a wiki is most definitely more personal based rather than as a community. A personal goal that definitely should not be a sole goal would be that of, make this much money off of Adsense. The reason that would be an utterly immoral goal, as it would probably lead to the creation of pointless pages, and endless information that does not pertain to the site given. If money was a driving goal of a wiki, then a site originally focused around music, may just be generalized way too much, to include members who wouldn't like music, like a videogame forum. No harm in having a videogame wiki, the only problem would be, your site now includes members who like World of Warcraft, and some who like Children of Bodom. You would be making almost a brand new wikipedia, which we all know, already exists.
Money isn't always a bad goal, but should never be the driving reason of creating a wiki. Personally, no matter what a person's definition of success is for a wiki, it is definitely centered around maintaing a wiki that is specific, sticks to one point, and pleases it's members by giving the information it promises to. Having such a goal to please one's members, is where a page creator's success becomes the success of the wiki as a whole.