I don't think it is the complication, as such, that is the problem - people are mostly smart enough to handle complexity. The fault is there is absolutely reliable internal logic to the armour crafting system, so nobody can look at making something and intuitively know what is good or bad or indifferent to do. The process can be as complicated as it likes if it has an internal logic people can grasp. UO crafting, especially for armour and weapons, completely lacks any consistent principles. Refinements just stacked another bizarre 'system' on top of an already overblown mashup of things.
It's a cobbled together mess, where some properties randomly appear on a piece of armour because you make it with a funny coloured tool (which nobody can make, apart from some hidden mysterious 'BOD Tradein NPC' who can supply infinite amounts), but that same tool can do more predictable and powerful things if you 'reforge' with it ; cloth, leather and metal can all be just as effective armour as each other ; you need an absolutely specific one of dozens of refinements to make a slight tweak to an armour piece yet other common materials make bigger differences just by being sewn or hammered on top of an existing plain piece (how the hell does THAT work, to enhance a leather tunic I need to use the same amount of a different leather type as I needed to make the thing, which comes out the same weight - no sense at all!).
I always argue there is a massive fault in any game system if someone new can ask the perfectly reasonable question 'what armour is best for me?' and need long explanations, references to web pages, spreadsheets, and online calculators to get to an answer. It might be mathematically sound, but it's not immersive, it's not fun, and if something fails on those grounds it really should not be in an online RPG where immersion and fun are two of the main points of the game. It's what happens when programmers try do a game designer's job.....