8-9 DR in Fallout 3 isn't really that good. I think the Merc suits should've been at 3-5 DT but 1 DT is fine. It just means your going to get cut up if you face a tough enemy.
yep. in addition those suits had also very low item hp in fallout 3, too.
after 2 or hits from a plasma rifle the suit would have been destroyed. so i'd say, there have not been nerfed at all.
merc clothes aren't armor, they are just practical clothing.