For me its not so much about the amount of people who play what I make but making something thats fun, ofcoarse you need people to play it to improve on it, balance and the like. Thing with that is alot of people wont try stuff out especially online, server admins seem very unwilling to pickup anything that isnt a UTComp, relics or invasion (basically anything thats a name brand in modding)
To that end even if the player counts were higher theres no guarantee what I make will see the light of day on any server, unless I happen to create one and put it on there myself.
Its not about popularity, if people get into modding to become "popular" they are barking up the wrong tree, modders are very unapreciated people mostly.
But ultimately, its depends on what kind of mod you make.. if i make a little mutator that tweaks gameplay a bit, then really, i'll be quite happy just playing it offline myself, and hopefully, some other people out there will have fun doing the same, and give me some feedback, maybe even a "nice work" along the way, then my little mod has done its job.
But if i was making a much bigger mod, the next RO, TO or Troopers, then thats a rather different ballgame, a mod like that needs players, and all the work that goes into something like that, man, i'd be pretty sad to see only a handfull of people enjoying it, thats, just gotta suck..
And then there's shades of grey inbetween the two.
I'll tell you what though, about servers beeing very conservative about what they pick? yeah, they definately are, and it has held true for any game i have played or modded, so, really, if you want your mod to get out there and be played, you need to not focus on servers to begin with, target the Offline crowd (IE: make sure it has good bot support), then it will get played, and if its good and enough people play it, and talk about it on forums and IRC, people will start to take notice, including the servers.
This doesen't quite work for all mods (Offliners woulden't be playing one that, for instance, tries to improove online lag, they have no need for it), but generally, this could take you places, get you needed feedback, and get your mod noticed