I have explosives at 65 and no explosives perks taken.
I mainly use guns, sniper type rifles with sneak. Shotguns and fullauto weapons on closecombat.
How ever I have found that explosives can be usefull if they are planned tactically, as support.
There have been many occasions where I saved my companions life from Cazador swarm with 2 frag grenades.
Deathclaws I always kill by planting some mines / c-4 to their predicted path to me and then get to higher ground and start sniping. If they see me or start looking they walk/run to my explosives that if not kills them, cripples them and buys me more time. I play on hard / hardcoe and only armor I use is my bountyhunters duster with 6 DT so if a deathclaw gets on my skin I die!
I never engage my companions to hard fights anymore since I lost Boone on my OMGWTF fight with cazadors. I just tell them to wait till I clear the path.
I haven't run to any deathclaws in close quarters yet, can't wait to see how I can pull that off

But anyway, Explosives are great for support but lousy main weapon. They also make a nice assasinaion tool

Live dynamite on targets backpocket usually rips him a new ahole

Also some c-4 planted while in stealhboys protective invisibility field can blow up multiple baddies or make them crippled and almost immobile
I tried to do powerarmor wearing minigun shooting badass who just walks and mows down all kinda toon but that failed.