This is only applicable to newer mame then, right?
"Newer" yes, sort of, but depends on where you draw the "new" vs "old" line. It's been around for just about two years. Joystick_map was added in 0.117u1. Qbert started with a rotated 4-way map, but it was switched to using the normal 4-way joystick_map in 0.118u3. 0.119 came on
13 Sep 2007, and 0.118 on
5 Aug 2007.
If post 0.106 is "new", then yes. If one year or newer is "new", then no.

I can only think of 3 games that use diagonal 4-ways: Q*Bert, Q*Bert's Cubes, Congo Bongo. All 3 are fun, but my system won't have a dedicated diagonal 4-way unless I were to go with swappable CP's (unlikely). I don't have a spinner or trackball either, so if I were to look into another CP, I doubt the diagonal 4-way would be high on the priority list.
Actually, Congo Bongo seems to work fine with either a rotated four way or a (not rotated) 8-way without any remapping in mame. At least last time I tested, a few versions ago. Pretty cool coding, IMO, so that it could be converted from both qbert cabs and a normal 8-way cab.
You can test it if you have a gamepad encoder or u360 in analog mode very easily. Set mame's joystick_map to "only diagonals" with: "
joystick_map 7777s..77775.777555.ss5" and leave mame's in game mapping alone. The double check by using the before mentioned rotated 4-way joystick_map ("
joystick_map 4444s8888..444458888.444555888.ss5.222555666.222256666.2222s6666.2222s6666"), again without changing mame's in game remapping. Both work the same.
(If you draw out the joystick_maps, they are the same as far as center and sticky spots, but the former sends diagonals when the stick is pressed diagonally, while the latter send cardinal directions when pressed diagonally.)
Still, for qbert and congo bongo, a true rotated 4-way
feels better than a circular 8-way (like happs super). Or at least those restricted like one (like u360's square restrictor). Happs competitions with noticeable corners aren't bad either.