Lack of Combat in Fallout:New Vegas

Towards the end of a play through I come to two problems. Too many weapons and not enough stuff to kill. I have an inventory of 20+ weapons and yet thier is hardly a creature in sight. Atleast in Fallout 3 there was a steady supply of respawning mutants, enclave and raiders. In NV there are what? A dozen hostile mutants. All my good weapons stand idle with an ever increasing supply of ammo. I just got This Machine and have killed maybe 4 things with it. I long for the beginning of the game where it was just me, my varmint rifle, my 9mm and a bunch of powder gangers, geckoes and ghouls.