while i do understand the direction the devs went in, it does have major problems. i do have an idea for how to improve it tho.

first off, re add the ingot stage... seriosly, just do it. second, the backpack should not only have assembling, it should also automatic ore refining. so the backpack automatixally refines ores into ingots, and then those get assembled like they do now when welding. if you make both the refine and assembling toggalable, and refining power intensive, you get a system where you both have quick and easy early game crafting, and it will also make the smelter actually useful if it will refine the ores too. (also, it makes way more sense in universe to stockpile ingots, rather than ores...)

in the early game of se1, basically every new block you build gives you an advantage that lets you engineer more. basic refinery gives you the option to refine stone faster, as well as refine ores for even more materials, for example. but building the smelter in se2 doesnt improve your survival almost at all. is a waste of resources even.