When people professionally demo the game on the easiest difficulty, where your direction is guided, you know your game is a flop.
One of the biggest issues people took with the later THPS games is that, well, I don't know exactly, but Neversoft wasn't exactly challenging itself.
The last one I obsessed over was THUG2. Opinion of Margera aside, they had great levels in the game, especially when you considered there were level-breaking events in each to change the terrain.
Keep in mind every THPS also kept the classic mode with the 2 minute timer AND had the more open story mode.
But once I played THAW, that's where it really died for me. The game just felt like a story and I had a rocket skate to get around. They went for a seamless world which is stupid for stunt-based game. It forced the player to start skating around to do TASKS that were not attached to the heart of the game.
I had a lot of fun with THP8, but it didn't recapture the speed of THUG2. Moving to HD, the framerate took a dive, and they removed a LOT of the features that made the early games great. It was really rushed. I pretty much never played Proving Ground, because by that point it was obvious they didn't care.
THRide tried to re-invent the series with a peripheral, but that's not what it needed. The gimmick, something Tony always wanted himself, was the worst fucking timing ever in this economy. At least DJ Hero was heavily marketed and had no previous shitty series to tarnish it.
What they needed to do was remake Tony Hawk more in line with how Burnout 3 changed into Burnout Paradise. Radical overhaul.