To go along with what Jigun has said (and I agree), it would be good to have more distinction between the different weapon categories. Frag grenades should be used for crowd control over lighter armor targets. I think power armor wearing enclave troops and mutants should be able to shrug these off to a degree. I don't agree with people suggesting that regular frag grenades should be able to slaughter everything in the game...armor should have an effect here, and also consider the rate of fire for grenades. You can lob them at pretty decent rate (1 grenades per second I think...and also very efficient with Kai Hohiro's FPS grenade hotkey mod) right now. Also, frags are very common loot. If you're an explosives user but not specialized in big guns, frag mines/bottlecap mines can be used to help punch through heavier targets. There are different types of explosives, so they should have different purposes. The missile launcher can be used for very big or heavily armored targets (enclave, behemoths, gargantuans, brutes/masters, robots etc,).
I think this would be the better way to go, rather than weaken the mutants and other creatures. Different targets should require different tactics and weapons to take down effectively.
Expecting to take everything out with an FN FAL or a couple grenades seems pretty one dimensional and boring to me. Big guns/explosives/small guns users should excel in different areas of combat, and be less generalist. I think that's the whole point of skill point reduction in the current FWE, to that characters can become more specialized over the course of the game, rather than turning into demigods that are masters of every skill.