If you look at the History of Grunts starting back to Halo CE and continue to Halo reach the physique of grunts hasn’t changed that much but seeing the new images of the Halo 4 grunts it looks almost completely different besides from the Arms and Legs. I only wonder as to why they would change the Grunts appearance so much. I understand that 343 is trying to make Halo 4 the best looking Xbox 360 of 2012, but changing the overall appearance of the grunts seems to much. Regardless of the new grunts Halo 4 will still be the biggest game of 2012.
I agree on everything except the slight criticism of the new Grunts. I don’t mind their new look. It really doesn’t bother me that it might not make sense in the long run.
Yeah its weird isn’t it? As far as I can tell they have simply been changed (like the MCs armor) for no other reason than artistic license.
Worst thing about it is that I personally would probably feel less charged about this issue if the change was a good positive change but to me they look terrible and a weird mashup of Grunt, Locust, Rancor and Shark.
I don’t mind it at all, it’s not like it really breaks canon. They’ve changed slightly in all the games, not to mention we don’t know what the status of the covies we encounter is
Try one of these two threads for all your grunty discussion needs. 
http://halo.xbox.com/Forums/yaf_postst76173_New-Unggoy-breaks-canon-MAJOR-UPDATE-Pics.aspx
http://halo.xbox.com/Forums/yaf_postst78272_Why-it-DOES-matter-that-343i-Changed-the-Grunts.aspx
And welcome to Waypoint.