Athletics is indeed very usefull, but once you have 4 WM, even if you have 24 agi, it's better to have 4 IF, than 4 more WM. The difference in weapon speed is hardly noticeable, while having 8+ health can just let you survive this damn MW Arbalest body shot.
Anyway, i did a 24/15 longspear build once, and it was definitely worth it. Eu tend to have more Agi based build, because people having heirloomed 3 times gloves and body armor (and helmet ?), can still survive relatively well with a 15/24 build, and still do damage. But Str still has the upperhand.