There's always room for discussion, but perhaps the section Metalworking in Pre-Columbian America from our FAQ will answer your inquiry.

Hey there,

Just to let you know, your question is fine, and we're letting it stand. However, you should be aware that questions framed as 'Why didn't X do Y' relatively often don't get an answer that meets our standards (in our experience as moderators). There are a few reasons for this. Firstly, it often can be difficult to prove the counterfactual: historians know much more about what happened than what might have happened. Secondly, 'why didn't X do Y' questions are sometimes phrased in an ahistorical way. It's worth remembering that people in the past couldn't see into the future, and they generally didn't have all the information we now have about their situations; things that look obvious now didn't necessarily look that way at the time.

If you end up not getting a response after a day or two, consider asking a new question focusing instead on why what happened did happen (rather than why what didn't happen didn't happen) - this kind of question is more likely to get a response in our experience. Hope this helps!

I've always thought that Heather Lecthman's (1984) article Andean Value Systems and the Development of Prehistoric Metallurgy addresses this question very well. You should be able to access that article on JSTOR for free.

Although her article is focused on the Andes, she addresses the entire Americas. The core of her explanation is that metal meant something very different to people throughout the Americas than it did to people in the Old World. She includes some other technological, economic, and material reasons that all also play a major role (there is never one simple answer to these types of questions; everything is complex and complicated and we only have a very tiny picture of what happened, anyway). But what I find most intriguing is her idea that metal simply was valued very differently than in the Old World.

Basically, according to Lechtman, metal in the Americas was seen as a symbolic material imbued with ceremonial power, and it was therefore prized for ornamental purposes (e.g. jewelry) and elite status symbols. In the Andes, at least, there were traditions of gold, silver, and copper work that produced extremely intricate and technologically sophisticated objects, including various alloys.

They made bronze (arsenical rather than tin bronze, but this produces a similar product). I've seen mace heads and tools (hoes and digging tools) made out of bronze, and tips for atlatl spears made out of gold or cobre dorado (gold and copper), probably used on upper class hunting trips. There's no reason they could not have made thrusting weapons tipped with bronze. But these weren't weapons and jewelry for the masses, they were elite goods and status symbols, and may have seen little use. Metal was simply valued very differently.

Before you think that it must be weird or something had to have happened for these value systems to be different, you have to recognize that there is nothing inevitable about how things unfolded in the Europe, the Near East, and the Old World in general. There are thousands of different outcomes and scenarios that could have happened to lead to the world we saw at contact between the Old and New Worlds, and just as many things happened in Europe to lead to iron and steel as happened in the Americas to lead to ornamental metal work (this is what Elm11 means by avoiding ahistorical explanations, which are those that ignore the specifics that led to the observed situation). Things unfolded differently in the Americas simply because that's the way things happened.