Then what do you suggest they do? Make Under Da Sea more avalible for stone rankers? ''But CubeCraft? I really want to play Tea Party more often!!'' same problem. Yes, not everyone can buy a rank but tell me what else either the players or CubeCraft can do? There's a reason you can pick maps with Iron+ rank. If they make it stone rankers can choose maps as well, it'll ruin a feature some people bought a rank for. It'll ruin iron rank because the map picker is basically the only thing that makes the rank useful.
You can't have everything, if you want something, you need to pay from time to time. Just like now. If this person wants to play Under Da Sea more often, he should buy a rank.