Why limit Paragon 2.0 to just the listed categories? While it will be nice to have some "customization", it still seems a bit dull. I am fully aware that this is not an MMO, but why not have something along the lines of "class specific" categories? Take the witch doctor for example. Paragon points could allow you to buff up your pets, or add utility effects to them. Maybe you want to beef up your DoT spells, or again, add some sort of effect or utility to them. These are just some quick, vague examples off the top of my head. If this were implemented I think it would need to be designed and balanced in such a way that it would not invalidate skill, rune, and passive choices.
I know that with loot 2.0 one goal is that legendaries will be "build changers" but even so I still think that paragon points should do more than add to our pre-existing stats.
With such a system I think it may be better to limit how many points could be spent, thus making the player think about how to best allocate them for their chosen playstyle. Wasn't that the reasoning behind limiting players to six skills instead of seven? To make your choices feel as though they carry more weight? Sure, cookie cutter builds will always exist. Some choices may always be more efficient or popular than others, but at least this would add variety.
As many others have mentioned, with the currently proposed system, eventually the "choice" doesn't do much because everyone has capped the same things.