If you need wifi, by all means, go integrated. But not everybody does.
I'm guessing that lots of Picos will see use as enhanced GPIOs for Pi "motherships," which provide backhaul to multiple wired-in Picos.
In fact I have a project which could use a decidedly non-wireless USB GPIO, for use on an airplane imaging system.
It can replace many IC and will make a very good addition to ESP32 which lacks pins for many projects. And, sometimes you want external chip so output is not affected by ESP32 reboots or freezes.
On the other hand I often find myself missing USB-related features on the ESP32, such as being able to act as HID device or even a USB host. The ESP32-S2 fixes that, although software support for that is still relatively immature.
For instance: https://launch.arduino.cc/nano-rp2040