They just seem to be really popular. The same thing happened with the iPhone 6S Plus. I finally got my hands on an iPhone 7 Plus yesterday. The store I went to here only had two of them in stock -- I had them hold one for me while I drove up (was only about a 10 minute drive up to the mall at least).
If you are fortunate enough to live near an Apple store they are available at most locations now. There are some areas up north where they don't have any stock, but the majority of the locations now have at least a few units in stock.
Alternatively you can order from Apple.com now and get one by the end of December. At least they're no longer on a 6-8 week backorder, which is nice.
Needless to say I didn't get the color I wanted because I had to just take what they had. Doesn't bother me though, because you never really get to see the outer shell since you want to keep devices like this in a case.
Oh and the dual speakers are nice. This phone is loud as hell! And I mean that in a good way. I only have to play my media at half volume on this beast to hear it well enough, as opposed to two to three clicks from max volume on my iPhone 6 Plus. Also, it seems to have true stereo sound. The only device I've had that rivals the sound on this thing was the HTC One M8 I had due to HTC's BoomSound. Haven't tried the LG V20 yet.
But this phone is by far the best cell phone I've ever owned.
