Essentia bulk storage can be a hassle. You either have to manage a lot of phials or set up a big system of jars. The essentia crystallizer from previous versions of TC could be of use. It seems to me that essentia crystallization would have been implemented to TC6 if it was countinued.

It would output Vis Crystals as they are they are dropped by mobs dying in Liquid Death, consistent with previous versions.

The main benefit would be easier bulk storage and easier handling of essentia. The main drawback would be the conversion from vis crystals to essentia isn't 100% efficient and creates flux. The smelting process also needs fuel and time.

The crystallizer could either use vis from the aura like TC5 or other forms of energy. Or it would be free to use like the centrifuge. You could also go the route of the crystallizer being slow without energy like in TC4. Another option would be to make the crystallizer slow with no way to speed the process up to encourage using them in bulk. This would make crystallizers expensive and inefficient to use, with the trade off of being easier to manage.

Now why you shouldn't add this:

1) It makes crystal farming even more useless
Now this is more of an issue with crystals themselves as they are pretty much a joke as you can just make tons of crystals through quartz slivers. Shard farming made more sense in TC5 as shards could only be gotten through farming. Crystal farming in TC6 should be rebalanced/overhauled, but I don't think it is the scope of this mod.

• One idea could be to implement compound crystals similiar to mana beans. The compound crystals cannot be crafted and can only be "bred" from its corresponding aspects.

• Smaller buff would be to allow gathering 1 crystal at a time like in TC2&5. It would be done with gauntlets or adding the crystalline bell from TC2. I don't really see a reason for not adding this.

2) It serves the same purpose as essentia reservoirs
If reservoirs are implemented, they would serve similiar purposes. While they would differ significantly, reservoirs would have the advantage of being more efficient at storage.

3) They would cheapen the cost of crafting
Crystals are a vital crafting component in many things. Making crystals easier to acquire could make things too easy. In TC4&5 crystallized essentia and shards are a different thing entirely, with crystallized essentia serving the sole purpose of storing essentia.
I don't really agree with this as TC6 is already very grindy. Also the cheapness of the crystals could be balanced with an energy and/or a time cost.

I could see an argument in favor of the essentia crystalizer as it was in 4 and 5.
For balance, keep the 2/1 ratio on essentia, and make it behave like the thaumatorium on a much smaller scale where the only thing it does is crystalize essentia that's fed directly to it.

One use case I would have is within my essentia setup, it would serve as overflow protection feeding into a chest while causing less harm to the area than using void jars.