These are great questions that we would all love to know. But realistically Relic doesn't owe us anything. They made the game and can just say "Its done, next project".
So why would they want to communicate with the community?
1. To keep interest in the game so that new purchases are made? #1 thing you see in steam game reviews: "This game is dead do not buy unless you want to play alone".
2. To make money on new content such as DLC, Skins, etc?
3. Maybe there is some small pride in the thing they have created
I would love to see more transparency from Relic but I also see the chat in their twitch streams where everyone is just bitching the whole time and calling them retards. Does this happen in other dev streams? Is it just the RTS community that is so salty? Did Relic bring this upon themselves? I am new to the whole community thing so I don't know.