I agree with Shoe. Tanks seem a bit too prevalent now. I always thought they were worth their cost in 1.3, but now they just own.
And Hirmentrium, it's not exactly the same role. The Carnifex Strangler has a considerably larger AoE, and let's not forget that it comes on a walking tank. Also, the Fex can easily switch roles and go AV with a (admittedly underpowered) Venom Cannon upgrade. Spamming spore mines is fun, too.