From the look of it, HoI4 is more detail and snazzier graphics (and sound - see the latest DD

). While I'm sure there will be some of us that wouldn't mind a bit more detail in specific areas of personal interest, I'd say that on-balance, the level of detail in the game is very good. I'd also say that the visuals for a strategy game are excellent.
So I'm not sure we have to choose an either/or proposition here. OP - a bit more specificity wouldn't hurt - do you mean "even more detail at the expense of graphics" (as, while the people doing graphics are different to coders, there's budgets and the like so it is theoretically possible to have less artists/modellers and more coders/designers)? My personal view is that they've got a very good balance, but everyone will have their own preference of course.
I am very sure, however, that as Mannstein well said, we're a bit past that point now, unless we want the game delayed until 2018!