Actually, the inclusion of resource cache's makes resource gathering incredibly easy, even without carrier. Finding a couple of Orokin Relays or whatever they're called for orokin cells or Argon clusters makes it so much more convenient. Just treat resource runs like syndicate medallion runs.
Too slow, IMO. I can make two runs in the time it takes me to ransack one full level. Only when it comes to stupidly rare stuff like Argon Crystals does it seem to be worth it. I've yet to find a cache of any variety that had a drop that made me consider the time spent worth it.
But to get back to Energy, I don't really find it common at the rates I consume it. I can go from literally inexhaustible energy due to collection through Carrier, to being out of energy when Carrier is destroyed. The difference is that big, even with the Void Discipline regen, even with stacked Energy Siphon thrown in, even with a now 350 soon to be 400 Energy pool. I can go through that much energy with ease. What stops me from draining myself completely is teleporting around the area with Bladestorm and Vacuuming up the energy drops from guys I kill, and that other people have killed earlier.
It's ridiculous overkill for perhaps 60% of the game. But when there are higher level sorties where guys do sick damage, you get no shields, 60+ minute survival, etc and so forth, being able to endlessly teleport around and deal damage while invincible has carried whole games for me. Again, what allows me to spam 4 an entire game is ultimately that energy pickup through vacuum. The whole thing drops in efficiency by like 50+% when you remove that element from the equation.