If you view the campaign as an artificial story mode I see your point here and I welcome the idea of an artificial kind of campaign, a la RTS campaigns like Warcraft III's that are completely different from a skirmish game. In fact this campaign mission was a good example of an introduction to such...

FFF explained this problem of very hard biters very well when it said: Actually no, it isn’t so hard for new players. It is hard for veteran players. The attack system emulates Freeplays pollution system. If you pollute hard, you are attacked hard. The only difference is that the 'price' of a biter ...