This is feedback. This is what you say people don't give.
Players should have every reason to attack the enemy. Anything that rewards the player for doing what they should (attacking the enemy/winning the game) should be rewarded. The problem is that players, particularly humans, delay the game. The major problem I have with 1.1 is that games don't close.
Aliens tend to attack more because their base is weak. They can't camp effectively. Humans are the usual suspects of delaying games because it is more effective for them to ride turrets and spam. So, I tend to advocate for the alien team more simply because the alien team does the right thing, which is attack.
If aliens have to build forward with eggs or humans build forward more with repeaters....good. That is the kind of behavior you want. If people advance on the map and kill stuff, good. Why wouldn't you give them credits for it? Why wouldn't you reward them and enable to them to keep attacking? The 'freedom to build forward' sounds more like 'they are afraid to build forward'. And there is always a risk vs reward when it comes to advancing. But if you don't give a reward for moving forward, why should be people do it?
Building forward helps people move forward and when they move forward, it helps them kill bases. So, if you give credits for killing structures, you reward them for killing bases (the end goal). However, forward structures might get killed in the process, thus rewarding the enemy team for doing what...moving forward. So, either way, moving forward and hopefully ending the game is more rewarding than camping. But the players have to risk something (moving forward). You can't have fun and risk nothing. You can't win and risk nothing.
By not giving evos/credits for destroying structures, you are creating a disincentive for the exact behavior you are trying to encourage.