Take this last game which I played as an example. I had 4 of my 5 Rhinos popped, forcing the marines outside their protective shell. One Rhino was the Death Company Rhino, and they are not exactly regular marines, so we will not consider them. However, the other three destroyed rhinos forced out one Tactical Squad and 2 Assault Squads.
I just felt like stating the obvious here (because if you are like me, you need to be reminded sometimes). We are not talking about Imperial Guardsmen. These are Space Marines. They are durable, tough, and capable warriors. They are able to accomplish their mission and bring death to the enemies of the emperor.
They still have that high stat line, as far as standard troopers are concerned. They still have the best individual equipment that the empire can offer. I have in mind here Power Armor and the Holy Bolter, or Bolt Pistol and Chainsword.