The electric tiles are intended to be kind of a mid game feature, where most of the players already are capable of producing high amounts of resources/products.
Making them cheaper could be good, yeah, but then they would become too trivial, just like producing concrete, but with the fancy extra of the electric conductivity. Personally, I don't even think things will change that much, soo... I won't low the price.
Plus (and this is more like a "lore" or "realistic" thing), in real life, copper coils inside machinery are almost always HUGE, so the electricity can flow more freely, and they are even widder/bigger when talking about "induction" (the principle behind how electric tiles work). So, making them require those amounts of material, considering the size of a floor tile, makes some sense. Lowering the cost would seem like chopping down the amount of copper in the coils, and by so, less potential electric current ...
... I know it's a nerd thing, but yeah, that's what Factorio does to all engineers xd
