They still do but there's nothing new about them except for that methane tank jump. It took 343i 3 months to add sleeping Grunts (featured in only 1 mission so far), which has been a Halo tradition since like forever. And it was done improperly. If you get spotted by an Elite, they all wake up. What ever happened to 'Elite shoots then the Grunts wake up'? Also, they never go back to sleep. It's psuedo-sleep!

Suicide grunts. <3 The first time I encountered one my mind almost exploded. It was that amazingly unexpected.

I loved that they'd say 'Ow!' when you shot them.