First of all, Olaf is a very old champ like poppy or Nunu. All of them have old visuals ( poppy after her rework not anymore) Also the skins are old and remember these skins are 520rp ot 750rp so very cheap old skins that have no VFX changes.
Riot said that they won't update champions only visual, they did it in 2014 and this was very time expensive and didn't help the game. Same with olaf, olaf is a very old champion, based on kit, lore and visual. So he need a VGU. I don't know if Olaf is Tier 1 or Tiert 2 but he is a champion that need a a VGU,
SO all in all, Olaf shouldn't get a Visual Update, because it just takes time and won't help that Olaf feels more like a League champ.
Notes:1. Skins aren't getting an update when it isn't needed. Just when new spells or particels are added. PF ez got one, because this skin was like a 1350/1800rp skin and not a 3200rp skin so they they tune it up to make him a more ultimate skin
- WW get no Visualupdate. WW got a VGU, sure it is a visual update, but 1. the charcter model was changed complete and 2. the lore and gameplay kit is also changed that affects the visual design