I would be interested in hearing why you believe this. Anecdotally, most of my players are strongly disinclined toward pathfinder APs because they are too scripted. While they all appreciate the production values, they usually get antsy and resentful of the heavy-handed tactics necessary to pull them forward along the story arc, and in order to get them to play wotc's adventures at all I had to persuade them that these were a totally different beast than the pathfinder APs.
I don't think what you're saying is wrong, necessarily, but it doesn't strike me as self-evidently true either. Why is a consistent, relatively DM-independent experience necessary for adventure lines to be most successful?
The "holding-out" of ToD as an Adventure Path was intended to mean -- and I think taken to mean -- that it would provide a similar experience to Pathfinder's highly successful AP line. While the jury is still out on that (at least MY jury is, as I have not read the published hardbound version of HotDQ to form my own views) the expressions of dismay in this thread would indicate that there are a lot of 5E DMs who were expecting something with less
requirements for customization in order to be playable.
Generally, I think that an AP --
any AP -- benefits from experienced GMs making changes as are required for their particular group. I recommend it often.
That said, a well designed AP should not
require intervention to be playable and enjoyable. It should merely benefit from it.
There is much that can be said about the relative strengths of AP vs ad libbed sandbox settings, but I was referring to "commercial success" in the quote you mentioned.
While I appreciate that many players (including yours) have different preferences, I think the market has indicated that the Pathfinder AP approach is the more commercially successful of the two in recent years.
You can go too far with it of course. It's only a hop skip and a jump to the original DragonLance, which while very commercially successful in its day - was the prototype AP the design of which has not stood the test of time.