Perspective: I'm a long time (late 70's) player of D&D, but I play infrequently. (Example, my son and I were active in Living Greyhawk 2-3 years ago, but have only played 2 times in last few years.)
In my initial scan of the Pathfinder rules, I find myself asking the same question in several places:
Example: Why replace Pick Pockets and Open Locks with one skill Theft?
What I would like to see is some more Designer's Notes on the changes. Perhaps in a blog like post, or maybe in a "Pathfinder Wiki", where the designer(s) provide background on why it was changed.
The old adage If it's not broke don't fix it is tried and true. I acknowledge several things may be broken, and require fixing. But for infrequent players like myself, I do not know what's broken.
Perhaps we could get a "Director's Cut" edition of the Pathfinder Alpha rules that includes more sidebars for annotated comments.
Sticking with my example above:
Theft
Problem (or Issue): Rogues rarely choose pick pockets skill as it is of little use in most campaigns.
Fix: Incorporate Pick Pockets into new skill with Open Locks. This restores an iconic skill of the rogue class.
Note - I made up the problem reason as I do not know what the problem is - but I would like to. For the changes from 3.5, I want to know why it is being changed.
I think we can all provide better feedback and be better playtesters if we understand the motivations behind the individual differences.