-There's a reason they're softer, which I've posted about several times (phone call from a liability lawyer) and I was part of the decision to lower the hardness (Rc) of the keys back in the mid 90's when I worked at Eklind as a die maker. That hardness may have been lowered even further since then, wouldn't know. I would also like to add that the steel used may/may not be what is usually used for a given brand. I've previously posted about an attempt by a competitor to corner the market on extruded hex coils (attempting to cripple Eklind) and we had to buy a different steel on the spot market to remain in constant production. The steel used during that period was inferior (IMO) to what we usually used so an inferior (IMO) product resulted. It could even have been that the heat treating was not tailored to THAT spot market steel during that period, hard to say when a variable enters the production stream. I'm not aiming this at
@CHI_Tool&Die, he's likely very well aware of variables in toolmaking. I'm only offering this to inform the uninformed that there's far more to manufactured products than just buzzwords and published/tested numbers. Published numbers are often used by marketing to guide the uninformed.
-I agree and this is rather dependent on the fastener itself, the socket opening dimensions across the different brands and fastener types isn't uniform. I've posted about this on a few occasions too.
-I've several different brands of hex keys, I still consider them all a perishable item to be modified or replaced when no longer useful.
-There's a couple of higher cost brands that focus on visual appeal. For those with higher profile jobs or just want the visual appeal that's ok too. Most of those jobs likely employ hex keys on, what I consider, a limited basis compared to what the average mold/tool maker does all day long. Constant industrial duty is going to wear out a hex key far sooner than spinning out the fasteners on a bicycle repair. I can understand the high end bicycle mechanic wanting the more expensive visual appeal hex keys but the industrial criteria is a different world. Both fastener and hex key are subject to wear/deformation and the the end result of the task. The task and environment often dictate what the appropriate tool should be.
-As for the ball end....I won't even begin to comment on what should be obvious besides structural inconsistency.