So then, the real number we should be concentrating on  is the spot price, no?
I think the main reason that people track futures is that the market is very liquid compared to the spot market, so it shows up price changes very quickly.

And there is some information in the futures prices.  When they DO move out of line with what you'd expect based on interest rates, it means something significant is happening in the physical markets, such as a risk of physical shortages severe enough that contracts for delivery can't be met.