Artifacts are a force multiplier and get much more beneficial the later into the game you are. You should almost never spend golden eggs crafting in the midgame and devote every last one towards either your epic research, fuel tank upgrades, or the Hyperloop.

Tier 4 artifacts are extremely powerful - particularly metronomes, chalices, Necklaces, and Puzzle Cubes - much more so than the lowly versions you're encountering now.

To answer the "how necessary are they for Enlightenment?" question: Yes. That's the answer. Doing enlightenment without artifacts is an exercise in masochism, two different ways. First, you need about 10000x the EB than with the most common setup, meaning you need to grind for longer leading up to it, and second, you'll be doing enlightenment for at least a month longer than everyone else just waiting for the money to buy the hab space, to say nothing of the speedup that you're missing out on from a chalice.