"Righto Sir! Bash that big pointy thing and knock down that wall and shoot those noisy squishy things!"
"One bad guy mash coming up sir! Load em up lads! We is going to be helping out the Sargeant here and taking out that there position"
Ogryns are not known for their subtlety. If you want strong assault troops who are able to broadly follow a few simple orders than they can deliver a few key positions for you on the battlefield.
Alternatively, if the enemy has crack troops making their way towards you then you can point and fire the Ogryn Squad in their general direction and watch chaos unfold as they launch into each other. More often than not the Ogryn Squad will steamroller over them and carry on looking for more things to shoot and bash.