Mowers, in all likelyhood, it would make for an exceedingly long game only attractive to a small number of players, and it would not be EU3 (play-feel, attracting the player base of the EU series) in anything but name. Victoria style Pops were a great experiment in simulation - which flunked spectacularly in execution and fun, and CK Dynasties, while interesting, tended to collapse under their own weight in micromanagement except for the most dedicated dynastical builders. The clunky interface helped towards that end, certainly, but the main problem remained ever increasing numbers of nobodies to manage events for.
Which are two of the reasons why neither of those two games came anywhere close to the popularity of EU2.
Repeating failure in order to be more "realistic" and "historic" seems like the sort of path that a smart software developer wouldn't take. Thus I fully expect Paradox to let EU3 remain focused on overall strategy from a classic "Kings & Battles" perspective rather than delve into making it more dynastical-management or population focused, or, if those aspects are further developed, it will be to a much, much, smaller degree than in CK or Victoria.
What I read into the "CK personality..." quote is something far more simple. Instead of giving a monarch the DIP/ADM/MIL stats, he'll get some base stats and a number of traits (reflective of the real person in history, no matter how "ahistorical" that may seem), with the possibility of adding to traits via random events. A large part of the charm of the EU series (however unrealistic from an ahistorical development point of view) was the "I know this general/king/event/whatnot from my history lessons and/or past games" - and I see no good reason to abandon such a good working mechanic just for the sake of something arbitrarily labeled realism.
Another example of this is the good old
contextual events vs. historical events. There's no doubt whatsoever which fits best in any sort of ahistorical history, given how often the latter are completely inappropriate to the sort of world the occur in, but nevertheless, they have a certain charm. Compare, e.g.
with the historic:
The latter event is obviously superior, even if (in your current game), your state religion is Banananism and the event really shouldn't happen just because it did historically.
*ducks*