Why can't I get a package with better upload speeds?

Why isn't Gigablast a symmetrical connection? Or why isn't there at least a more significant upload speed increase vs the classic 300Mbps plan? How about an option for something in between? I don't actually need more download speed... 300M down is plenty, but I would pay a little more to have something like 300-500M down with maybe 100-250M uplink for example. On the other hand looking at fiber internet service in other areas where cox doesn't have a near monopoly, fully symmetrical gigabit connections (with no data cap) can be had for around $70/month. Why do I have to pay over $50 more per month (over $100, if I want unlimited data) to get an inferior service? I hope Cox will take this as constructive criticism as, in the meantime, I am actively seeking other service options and sending requests to competitors to provide service in my area.