The time is at a perfect amount. This allows time for people to Gather their friends into one lobby. Maybe let the dogs out, or get a quick bite to eat before going right back into a Game. In my opinion, Anything less then five minutes is far to excessive. They've designed the lobby for if you're indeed in-game, there's a bunch of stuff to do. Like the parkour course. There's also a lot of Easter eggs to be found around the lobby, so this allows for something else to do in the mean time.
In the long run, if they did indeed decrease the amount of time in between games, this would cause' users to get bored (Although you may not notice it). The less you do something, the less chances you're to get bored of doing that thing. I think it'd be nice to have something like a 'Preview' of each map, like a little room covered by glass, with a sign stating the map name, and then some terrain. For example, so SG4, it could have maybe a Crane? Or some sort of construction site at Corn? Who knows, I may bring this up as a suggestion now that I think of it. This will allow for better/more accurate voting in the Pre-Game lobbies. But that's beside the fact, I don't see the time changing, anytime soon.
