Alright, there's some stuff I've gotta clear up here:
-Warcraft was never meant to be a Warhammer Fantasy game. The truth of the matter is that Blizzard originally considered making it one, but decided against it because they wanted control of the IP. However, the difference is that inspiration was taken directly from Warhammer Fantasy nonetheless (namely the orcs).
-StarCraft was never meant to be a W40K game either. Oh, I don't doubt inspiration was taken from it, but, well
http://starcraft.wikia.com/wiki/StarCraft#Development should cover it. In the case of the zerg they were originally bio-mechanoids, so any tyranid inspiration would have had to come after the original inspiration. And it's a mix of ideas anyway, as 'Alien' has been directly cited as a source of inspiration, and parallels have been drawn between the Overmind and the C'thulu mythos as well (personally iffy about that myself, but then again, the VitD is a clear C'thulu inspiration, so go figure).
-Primal zerg, Swarm Zerg...no, I'm not arguing this again, I've already explained at length why I like the concept of the primal zerg, but the insectoid idea needs to be clarified:
-Stage 1: Original zerg insectoids
-Stage 2: Zerg develop burrowing ability, enslave native Zerusian fauna, morphology changes
-Stage 3: Zerg end up being split, Swarm zerg are modified into "essential fighting components," ergo their insectoid appearance
I can speculate that a "stage 4" arguably exists that the primal zerg end up going down their own evolutionary path, so that by the time of HotS, they've diverged in as much from "stage 2 zerg" as the Swarm zerg have, which would constantly be changing from the point of leaving Zerus (e.g. zerglings were a relatively recent addition by the time of SC1, so I'd speculate that a previous strain existed before it was discovered that the dune runners could provide the basis for a better type of strain). There isn't much reason to think that insectoid parasites would make the host insectoid in nature. Adopting more reptilian or mamalian biological traits is going to do far more for individual survival than remaining as an insect, which can't reach that large a size even with abundent oxygen, so while it makes sense for the Swarm to become insectoid (as individual Swarm zerg are easily expendable, and insects would require less resources to maintain as such), a primal taking on traits that would help its individual survival even if not a species-wide survival makes sense for their mindset.
Which is one of the reasons why I like the primal zerg - I never saw them as a case of "superior zerg," I saw them as being the opposite side of the same coin. Both branches are dedicated to genetic and physical improvement, both sides are amoral in the pursuit of that goal, the only difference is that the Swarm carries out its improvements on the macro level, the primals on the micro level. The Swarm is a hive mind and operate in broods, the primals value individuality and operate in packs. What strikes me as odd about the "superior zerg" argument is that the same plot point occurred in SC1 with the Nerazim being "superior" to the Khalai (only they can destroy the cerebrates for example), and I don't recall any outcry about that revelation. If anything, people should be complaining about the primal/Swarm divide mirroring the Khalai/Nerazim divide. Maybe it's the whole status/apparent proximity of Zerus, but while that's indeed problematic for the setting (not to mention that Zerus is mentioned as being a lifeless rock by the time the Swarm leaves), that's more of a problem in of itself than something that includes the primals by default.
Or it's something else and I "just don't get it."
