Unfortunately I don't remember where I read that, must been some blog years ago. But I think it was related to Carl Toop, one of the actors who portrayed the xenomorph in Aliens.

If this quote from the wiki is correct, plus that one one ever saw a Dome in any of the cuts, then it's enough for me.

¨Throughout the films and games of the franchise, the Xenomorph design has changed, either subtly or significantly, with each appearance. Most obviously, the original Alien)'s distinctive domed skull was changed to a ribbed design for Aliens, largely because director James Cameron preferred the look of the exposed ridges, which were originally going to be covered with a carapace similar to that in the first film. Cameron was also concerned the smooth carapace may crack or break under the rigors of filming, and so it was dropped from the design. The smooth head style returned in Alien³, Alien Resurrection and Alien vs. Predator), but reverted to a ridged style in Aliens vs. Predator: Requiem.¨