10k overnight could mean that value has been created instantly by copy-paste, or it could mean that people are throwing money at anything they think could make them bitcoin millionaires. I wouldn't read much into such a low cap after such a short period. The market for currencies has already spoken several times throughout history, with most cultures tending towards fewer metal backings over time.
If the reason for multiple coins is just theoretical future problems then it makes sense to have some altcoins as insurance, but to use the most popular suitable coin for everything else in the meantime. If anything, people would trade a basket currency of multiple coins, rather than limiting each coin's use to a particular class of goods. We didn't see people using tin coins for stagecoaches because they were worried about gold transmutation or El Dorado.
Except those aren't theoretical future problems, it's happening right now in front of our eyes, at a speed that stresses the developers to keep up.
Back when ppcoin was released (just less than a year ago), any new coin can barely get past $50k market cap for months. Now they get to $1M market cap in days. You can ignore these signals all you want, but I take those 'whispers of the market' seriously and study them, because I have a lot of faith in free market. Even if you don't care about the low end of the market, just look at litecoin's market share, it gained on bitcoin massively since last year. Both facts indicate that market now has much more preference for diversity than last year.
So what happened since last year? 1) debut of ASIC in bitcoin mining; 2) bitcoin blockchain hitting scalability issue. The situation in cryptocurrency is quite different from metals. Different metals have different properties, only gold and silver are most suitable as money. All the clones of bitcoin basically have the same property as bitcoin, so if you have to make analogies to metals, they are more like coins from different mints, of different grade/purity, but of the same metal.