Why doesn't Cox support 16x4 DOCSIS 3.0 modems?

It is strange to me that the MSO competition (although not in this market) has significantly faster HSI options than Cox, and currently support the newer 16x4 DOCSIS 3.0 modems. If Cox was serious about this whole "Gigablast" rollout by the end of 2016, then one would assume that this would be something of a priority for them. As a long time customer of Cox, I was disappointed to hear that the Netgear CM500 modem (16x4) was not on the approved list, but the Netgear CM400 (8x4) is. I planned to fork over whatever it cost to retrofit for this gigabit internet option, but after seeing that I would need to spend even more money in a year to probably not get a fraction of the advertised speed was disheartening. I wish we had TWC or Comcast as options here in the valley as I would change providers right now. This may sound like a rant and quite possibly is, but the only difference in hardware between the two modems is the amount of downstream channels they have. This is ultimately irrelevant since the ISP determines your internet speeds. The most frustrating part is that the approved modem which can handle half the speed of the non-approved one; is only $20 less than the better one. Thank you Cox for still finding a way to cost me more money....I hope Google Fiber or CenturyLink rollout before Cox does, because that is where my money will go.