I agree on all counts, OP. It seems like SSX3 will forever remain the peak of the series given SSX (2012)'s poor sales. The real shame is that I doubt EA will ever care to look into why it sold poorly despite the series' former popularity. From a business standpoint it was a failed reboot, so the series is likely to be shelved again indefinitely. But from a creative standpoint it was really the fault of the designers for not playing to the series' strengths and marketing it to longtime fans as a true successor to SSX3/Tricky's legacy.
The fact that they didn't even include traditional synchronous racing out the gate and did away with split-screen play altogether clearly shows that their focus was in the wrong place when designing this game. Between that and the gimmicky survival elements, it was like the developers just completely lost sight of what made SSX so much fun in its prime.
That's not to say that SSX (2012) was a terrible game. It's still the best snowboarding game to come out this gen, but it was a missed opportunity to revive a long-missed franchise.
