We have an entire playerbase to consider, and if the players are bored, they aren't having fun... which is kind of the point of a video game. it's incredibly disrespectful and selfish to handwave that. Some servers hold rounds longer than two hours because that's what their playerbase wants. And yet others hold rounds that last maybe an hour at most.
Our playerbase tends to prefer 2 hours, and considering the overwhelming number of votes to end the round almost every round, this is plain to see.
Two hours is well more than enough time to build nice things.