I haven't seen the latest on the iPhone or the pricing, but up to now I've been planning to replace my 3 year old iPhone 12 Pro Max with the 15 Pro.
Reason #1 - it's out of storage space. I keep all of the photos I've ever taken with a smartphone on iCloud, along with some videos and a fair few galleries of photos taken with the DSLR. I want them with me. I pay for the 2TB, but the phone is only 256GB and right now it's at it's bursting point. I keep everything in full resolution because I'm not prepared to wait for it to download them, plus since moving to the 12 Pro Max the sync with Windows has been shit and I have to use PhotoSync.
I'll either get the 512GB or 1TB. Probably the 512GB, in the hope that the sync is sorted and with increasingly fast mobile internet I don't need everything in full-res.
Reason #2 - better camera. The camera on this phone is great but I've had flagship phones ever since I started and the reason is that if I'm carrying it around with me I want the photos to be as good as is reasonably possible, so they're decent in 10 years time. I've just been going through and updating a load of my old car thread with new image URLs (story for another time) and they hold up pretty well. The new iPhone has a better camera and since the 14 the telephoto has been made better, I often use it and I would like better photos.
Videos don't quite matter as much as we're pretty much at a 4K60 ceiling at the moment for everything, but an improvement is welcome.
Reason #3 - I want a smaller phone again. The 12 Pro Max has been fine but it falls out of my pocket in the MX-5, it's technically too big for the charging dock it sits on, it's way to easy to knock off when it's mounted in the MX-5 and it doesn't fit in the Sony head unit I bought.
I should point out that I don't care about USB-C, as mentioned in New Toys I haven't plugged a lightning cable into this thing for years.