primal culture used to be able to reduce mountain ranges to swamps - they epitomized the terraforming theme in a cool way and had to go and seek out nodes etc to get the most out of it. Terraforming skips mountains now, and a society trait does the fantasy infinitely better (umbral disciples with altars of marching gloom), and now giants also put the primal culture to shame. Their combat summon was admittedly OP to start, but that got killed too - there's no reason to play them