My HD650 is more than 5 years old. If I could not exchange the pads, I would be forced to throw it away 3 years ago and buy a new one. My K701 was more than 7 years old until its drivers finally died recently.
I have some really old headphones like HP1000 and K501. Without proper supports I would not be able to use those a decade old headphones.
The 650 pads need replacing about once a year, it seems they are designed to flatten and collapse....they you can cough up $60 for a new set. The X1 pads seem very sturdy. But Philips is also a relatively new player in headphones, so if they sell lots of cans, they would eventually have to provide some sort of support for them.