Basically, it obscures your view and locks you out of the game unless you decide which path you want to upgrade.
I find it very inconsistent with the rest of the game, where you can decide when you want to make your decisions. I would like to evaluate the geo-political situation first, is this a border town, or some lush farmland in the center in my empire? The game does not present this opportunity.
Overall, the UI of the game is not very consistent, with this being one of the biggest annoyances for me.