Foxcraft was one of the few servers that did Global Ranks, Many servers that I've been on do separate ranks for each specific server and they're much more expensive than the prices for each server Foxcraft is offering, If Foxcraft Is adding more perks for each server and even more features I'm definitely on board with this idea it will also bring new players to the server so I don't see an issue with this.
Edit: You also need to understand that not many players go on other servers, Most players only play one specific server or 2 if they become really bored, It's a great feature to add for players who play one specific server and can get a cheaper upgrade for that server rather than paying more for global which they won't even play on