With the new caves, mob spawning really needs to be tweaked

For one, I think the new cavegen really shows a problem with the way mobs spawning in tied to light levels. Instead of spawning at light level 7 and under, they should only spawn at light level 4 or under.

Lighting up builds or caves up to level 7 will be hugely demanding, especially considering that Torches and other light sources barely mob-proof a few blocks. Some light sources, like Candles, Glow Lichen, Soul Torches barely give off enough light to mob proof at all, meaning that their use for decoration is limited.

Why light level 4? It's the light level of midnight, so mobs will spawn during the night as they do now, but will probably spawn earlier and in more numbers in wooded areas. It also means that in deep caves, mobs would spawn in groups rather than spread out, leading to more dangerous and more avoidable encounters (risk, reward).

For two, the size of caves and the underground mean that the mob cap is usually taken up. Reducing the spawn range of mobs from 128 blocks to something like 96 blocks would be a really welcome change for the technical community by reducing the amount of spawn-proofing needed for farms, but it would especially serve to increase the threat of mobs in the early game by ensuring that they spawn closer to players.