Excellent thought, but I have a couple of quick responses. First of all, although the shearling interior is soft and comfortable, hopefully a pair of several hundred dollar custom orthoses or even a quality OTC device that fits properly should also be comfortable, while adding the additional support to make you MORE comfortable!!
Secondly, have you ever actually examined a pair of Uggs that have been worn for any length of time? In reality, the shearling foot-bed compresses down significantly leaving it pretty flat. It really loses most of it's cushioning and the actual comfort plantarly isn't that "great". I've had many patients enter my office to see if I had a comparable replacement insole to add cushioning, even though the remainder of the Uggs were in good shape.
And my wife would LOVE if our winter soccer games had bleachers!!! Although my soccer career has wound down, most of my son's games that were played in the winter were on pretty wide open fields that rarely if ever had bleachers. That required standing in freezing cold weather for about 2 hours, so her Uggs were more function than fashion.
Even some of the players wore Uggs during half-time to keep their feet warm.
I simply couldn't do it.....I'm way too manly