Actually, to the best of my knowledge, you're correct, and there have never been specific trait types like that in D&D before (excluding alignment, of course). [/pedant]
The 1e DMG had a bunch of tables for randomly determining personality traits for NPCs, and the official NPC Record Sheets had a section for recording the values for each trait category. When I was younger, we would sometimes use those as inspiration for fleshing out PC personalities.
Then I discovered Central Casting: Heroes of Legend, which was both a good thing and a bad thing...
EDIT: OH! And Thunderwave? (OP as a 1st level spell, imo) I'm no "physics has to work right with magic" proponent...breaking the rules of reality is what magic (particularly arcane) is for...BUT, that said, we know how sounds waves spread through the air. Why in the nine hells is the area of effect a cube instead of a sphere?! [yeah. yeah. I know. "It's magic." But...yeah...seems a simple/dumb error]
I just view that as a convenient abstraction, the same way that I viewed things like square fireballs in 4e. Minis on a grid are an abstraction as well; the position within a square on the grid is simply the "average" physical location of that character over a 6-second span of time. The character isn't standing still in the game world, and probably steps outside the boundaries of that square quite frequently.
In the game world, the effect is spherical, and any time a character is caught within the area of effect of a cube when they wouldn't be caught within the radius of a sphere simply means that at the specific moment that the effect took place, the character was within the area of effect. Cubes are easier to measure, especially if using a grid, and it helps avoid slowing the game down by having to figure out how much of each square on the edge is within the area of effect and whether a character in that square was within that part of the square.
Thunderwave is inconsistent with how Fireball is described (15' cube vs 20' radius), but that might be because Thunderwave also pushes the targets 10'. If you're using a grid, determining 10' from the edge of a sphere starts to get cumbersome, as opposed to just pushing two squares from the edge of the cube.
That's my best guess, anyway. I could be wrong and it's just a dumb error, but I wouldn't be surprised if the forced movement had something to do with it.