Regrowth - Legit way to progress in the dream world

Solution 1:

You are not missing anything obvious.

The Spirit World, aka Dreamworld, in Witchery simply mirrors the generation of the Overworld. The Spirit World exists primarily to get materials that only generate there, and items that can only be crafted there, i.e. Wispy Cotton, Disturbed Cotton, Brews of Flowing Spirit, etc. Because of Witchery's nature emphasis, crafting most of these items are not that difficult, some iron is required to build a kettle. The Spirit World does not seem to have been designed to play permanently in. As you pointed out: it is difficult to get enderpearls. This is because "Endermen cannot enter the Spirit World."

TL;DR The Spirit World is designed as a challenging way to get top tier ingredients in the Witchery mod. It is not meant to be the primary world of play.

Sources:

Playing with the Witchery Mod previously

https://sites.google.com/site/witcherymod/spirit-world