I think they may possibly have been trying to differentiate between individual Jem'Hadar... or else following, I think Moore's explanation of the horns around their faces, I think he said you don't walk into a Jem'Hadar- cuz you'll end up bleeding- so now they seem even more pointy and scary... But they seem silly. Especially those ones over the lips!!
You could be right about the AQ vs GQ thing, but none of the Jem'Hadar in the ep that intro'd the AQ soldiers had them (1 Little Ship)... one had ugly yellow head spikes though. I've never gotten over that. (Why did he have a uniform like the GQ elder??) And why are the AQ ones so arrogant? They're like Vorta! Do the Founders never learn???
On that note I prefer the later changes they made to the Founders makeup to the initial appearance... the deep set eyes etc.