Why do Aspects no longer have levels? Why are Fate Points now used to activate aspects?
RD: So, in play, we wanted something to make aspects come up more often, and one idea that was floated was "Spend a fate point and uncheck an aspect" This worked phenomenally well, but after doing it for a bit, we realized that we could skip the boxes entirely by acting as if the boxes were checked and granting a FP for each box.
Which in turn, mechanically means, 10 new aspects plus 10 fate points could be mechanically identical to 10 boxed aspects, but in practice was superior because it allowed more flexibility. That meant there were no more levels, but that was a bonus - it forces someone who would otherwise take strong  to take 3 different strong things, and that worked out very well.
So that one totally came from play, and it's worked really, really well. Implicit in that is why there's no more bidding.
Why did you remove the mechanic of "aspect bidding"?
Will Fate 3.0 have multiple combat/injury systems?
RD: Fate 3 will absolutely have different ways to handle combat and damage. In this regard more than maybe any other, SOTC is a very specific build, not a truly generic engine.
RD is Rob Donoghue