The steal system could have been much better then what was given to us. You have to wait for the right time to steal an item, get the enemy to function in a specific way to steal an item, or hit the enemy several times (or in such a way) in order to steal from them. A waste of time and sometimes very frustrating. Especially when there are multiple enemies on-screen and you need to steal but everything else is getting in your way. It was needlessly complex when it should have been straight-forward simple. Plus there are enemies that you encounter before getting the steal ability that never show up again so you can't steal from them. Specifically the boss of the Abandoned Castle. You never see him after defeating him and you can't steal from him unless you go through boss rush after the fact, and then what's the point? You've already finished the game. It was a poorly implemented design choice IMO. Also it would have been more beneficial if Julia's shop sold some of those extremely rare elements in order to forge new stuff. Her shop was pretty bare bones to begin with. Renaldo's shop had much better shit.
In SotN you need to beat the game once to buy the duplicator, It is hard to get glyphs in OoE when enemies are nearby and some weapons in DoS can't be bought, you will need to grind for souls and sometimes even beat the game more than once AFAIK (I've never got all of them so IDK).
Even so I don't think that they are a "waste of time". They are optional and add to the game, even more as a replay value if you want to get everything. Its one of these things that are hard to do but give a feeling of accomplishment when you steal from a boss.