My current character is a Necro-Warmage sort of affair, so it just seemed logical to take Frost as his primary offensive element; cold grip of death and all that. Even with some mods on PC, I still didn't feel like the magical badass I was expecting, although it was certainly better than vanilla; but then I went into a Dwemer ruin.

Dwemer Constructs are virtually if not completely immune to Frost damage, so I was forced to switch to the only other Destruction spells I had; Flames and Firebolt, and the difference is truly ludicrous - almost everything is vulnerable to Fire, and that combined with the secondary effect of DoT(Stamina damage and Slow is fine, but a Heavy Armoured Warmage isn't so desperate to keep enemies out of melee range as a pure caster) I barely have to look at things and they die. It seems like Frost and Shock are only actually necessary when you run into something that is significantly resistant or outright immune to Fire, and the amount of enemies that fit into that description compared to the ones who are resistant or immune to Frost and Shock is massive.

I mean seriously, with all the Frost perks you would think that element would at least be superior to Fire against bog-standard enemies, but I can kill things quicker with Firebolt(Apprentice) than I can with Icy Spear(Expert).

That's right. It seems frost and lightning is only for certain situations. I do know lightning is very effective against dragons, as it drains their magicka they won't be able to shout or use their fire/frost breath.

Try shock. If that doesn't work, Then fire is the best.

Because Frost is just good to slow people down.
Shock is good to drain magic from people and some good damages also it looks cool
Fire is great against anyone, Except those Dark Elf's, Idk why but it does tremenous damage, Like a Gnasher from gears of war when actived. 2 shots and you down/kill

You might also want to try (This only classes)

Like Breton's are Conjuration. Make an Undead army for your Breton.

I recall that frost enchantment does precisely nothing to slow enemies down (but literally brings your movement to screeching halt), so yeah.

In short, enemies rely on frost, you rely on fire. Sounds fair.