a simple solution to that "problem" might be just to nominate your maps a little bit before when the voting about the next map is coming, and because people rarely think and are clicking "4" to choose the first map (hell there's even a reminder in the map selection window, which says: "don't vote thoughtlessly and select a map which you want" or something similar to that), they will most likely choose your map, if you really have problem with the likings of the other people.
Increasing the cooldown is not necessary, as we deprive that way the players from choosing their favorite maps, which aren't probably a lot, and the current cooldown is actually long enough, the point is for everyone to have their fun and not deprive anyone of anything.
And a tip from me, when suggesting something (as you're right now suggesting for longer cooldown, could be for other weapon suggestion's stats, etc), at least have in mind a precisely defined amount for that subject to add/remove, followed with of course a good reason behind it, as we might lead this to completely chaotic situation with a lot of different opinions, and you get the idea of what happens after that.
What is the meaning of this, if I understood correctly, you just said that you want the whole nomination process to be removed and make it all RNG based?? I said above and will say it again, we're talking about the players and the freedom of nominating their favorite maps, instead of waiting for hours for hopefully some map, which they *might* like. That suggestion is something that I will instantly disagree with.