It's about the all important feel of character progression, the very feeling that Ob destroyed with its ill considered level scaling.
As you become stronger you do more damage, a feeling that can only be realised by pitting your character against a fixed challenge you once faced at a lower level.
As you become more fit you can travel further and faster, a feeling realised when crossing a known distance.
As you 'work out' against the dangers and terrain around you your agility may improve. More nimble, more fleet of foot, a feeling realised through a more fluid and responsive character and yes, realised through the ability to jump higher and further.
Please don't tell me that Todd, in his infinite wisdom, has restored one way of gauging character progression through limited level scaling only to remove another, equally important, gauge of character progression by fixing speed and jump height?