(View this on your iPhone)
Well, you're one person. How about the other eight billion people on the planet?
Everyone is not you.
Some applications do want a code that's slightly less trivial to yoink than "look at a screen once, have it forever". TOTP would raise the bar there.
Someone else mentioned TOTP codes that are hard to copy
My personal gripe is that NFC readers can't read wallet passes. That's also true for google/android.
Both apple/google restrict it and only few very big retailers are using it.