Using a slider isn't sixy, but it is haggling, Standardized discounts are not an abstraction of haggling, but non-standard discounts that took into account race, speech, gender (non-perk), and disposition would be an acceptable level of abstraction for me.
"Page turning" is actually quite nice if you like reading. And TES always has decent stories in their books, and they often get overlooked. I don't want to force anyone to read, but I still think there should be an in game reward to do so.
I see it as being an abstraction for the haggle. The perk just assumes you're so gifted at haggling you'll get the discount no matter what their disposition is. If they could find a mini-game that actually made haggling fun, that would be cool, but bumping price points up and down just didn't feel compelling to me as a game mechanic.
I don't think its "exactly the same at all". Interacting in combat is fun. Turning pages just doesn't engender the same feeling of action. To force someone to page through the skill book is only turning a one-click job into a 10 click job.