is a guilty pleasure, Having his ult practically on the same cooldown as his hook feels strangely amusing, coupled with zombie ward or ghost poro (Because support) or cheap shot (If AP mid).
Is another guilty pleasure, with ultimate hat and cosmic insight, his ult gets to around a 30 second cooldown at max rank.
Im not quite sure why they moved it however, it dose seem to fit better under sorcery, it also feels like Nimbus cloak would work better under domination, so thats up for debate.
As for why you would take it:
Some solo laners don't want ravenous if their primary damage is entered around autos since Rav heal is only on spells, examples would be Aatrox and Tryn.
Some support don't take the item cdr mainly tanky ones who build items like Zekes and knights vow, maybe even locket, champions like Blitz and Leo come to mind here.
As for jungles wanting movement speed, I do agree here, they like getting where they need to be and quick, or maybe you just want to be a fast horse. The only jungles who I would invision who's ult massively increases their banking power, or in the case of Ivern, have a pet that they want up more often, some champions that could come to mind here are Nocturne, Skarner or Yi.