Hi Jayat, fellow crafter here. Power is intended to act as a sort of class tier for crafters much like how other MMO’s have tiers of armor gained from beating harder and harder bosses. It’s basically impossible to get the best tier3 stuff without first getting most of a full set of tier 1 and then tier 2 stuff. Crafting in boundless works much the same way.
First you finish Tier0, acquire all machines. Tier 1 is to add spark cores to your work shop and generate enough spark for your basic needs. Tier 2 is a set of basic engines. It’s important to note that you can only have a maximum of 24 engines per machine, so to get those highest skill cap items, you need to hit tier 3 by acquiring advanced engines.
This provides a natural progression curve to the game that you don’t typically find in most survival crafting games.
Also, as @will mentioned, a Tier 3 workshop should be a big, impressive build with lots and lots of mechanical bits and work stations. Only the most dedicated crafters should reach the final tier, or even need a giant workshop like this!