Hi there,
I agree with this suggestion, for both EggWars and SkyWars. There tends to be a few maps that some players may not like, but other players do like. A lot of players end up having to join the game and quit the game to find maps that they like (I've had to do this a lot trying to find the Easter Maps). Most other servers require you to vote for maps, but because CubeCraft's SkyWars and EggWars take you directly into a match without a waiting lobby might cause problems with voting. So selecting maps would be the way to go.
I feel that selecting maps should require the rank of the gamemode (excluding Survival Games and MinerWare). When you select, for example SkyWars, then tap the mode, for example SkyWars Solos, players with the SkyWars Rank can then simply select the match they want to join, with the buttons explaining what map the match is in. Keep in mind that not all maps would show up, because there are simply too many maps to all be playing at the same time.
This would potentially change the entire way that SkyWars and EggWars runs, but I think it would be a great feature for those with the SkyWars/EggWars rank.
Good suggestion, +1 from me :).