If you're a small fry studio making a niche multiplayer game, DO NOT make it 64 players or, god forbid, go full retard and make it 100 players like Beyond the Wire. Let me explain it this way: you already are going to have smaller player counts, but what do people really care about? Availability of games. Suppose X > Y. Then A/X < A/Y, right? Less players per spot, right? So you're going to have more trouble keeping a variety of servers full, RIGHT?
They don't seem to get this. If you're niche, FEWER. And if you need scale, bots (preferrably visually and possibly gameplay distinct from human characters) are the cheap way to create scale without changing the fact that you may only have 32 players instead of 3200 or whatever you set your goal as.