Q: Is there a reason to not upgrade to Iphone 7 if on upgrade plan?

I can't see any reason not to upgrade other than wanting to pay off your existing phone and get out from under the need for monthly payments.

The CPU in the 7 is significantly faster than that in the 6s, and water resistance is a big bonus. The better camera is nice, but I'm not much into taking pictures of everything under the sun...

As Tim has said, some have reasons. As far as your comment about paying, you will either keep paying until it is paid off and is your phone, or if you get the iPhone 7, you will keep paying. The other difference, is if you pay off the device, if you get a 7s, or whatever it will be called next year, you won't have to trade in your 6s.

The decision to upgrade is up to you and whether you find the iPhone 7 will more meet your needs than the iPhone 6s. Since I've gotten used to paying the monthly fee, I plan on updating.

Along with a faster processor, longer battery life, brighter screen, you would be getting a brand new phone, with a new battery. While your current one has been in use for a year, with a year's worth of battery cycles accumulated.

But it's a personal decision. You are not required to upgrade and can just pay off the existing device.

Most carriers are no longer offering subsidized phones. Almost all phones are full-price units, whether you use Apple's Upgrade program, or the carriers' programs, like Next, Jump, etc..

I wouldn't say that it is wasted money, since you are still paying for the phone, but with an interest free account. Also, carriers are recovering the money you save on the phone via your cell contract, so you are really not saving anything.

Only you can make the decision. However if it was me I would upgrade and I did, I get mine on Friday. To me the pros outnumber the cons but as I said, that is a personal decision.