Hey, they can vote for what they wish to vote for. Admittedly, the players supporting it haven't done a very good job of saying reasons why you would want to wish, something they should probably talk about if they want to actually get any support.
Devil's advocate reasons, as I see them right now:
It's a strong possibility that we're going to be attacked by a Witch soon, so if we try the mana route we need to be fairly certain we can have some basic defense spell within like the next days/week, or else we can readily escape. Wishing gives us substantially more power, and makes this easier.
It is essentially the only way we're getting a cooperative Kyubey, ever, and having access to Incubator knowledge and resources is a huge step up. Plus that might make the witch bombing easier, if we learn it from someone friendly.
Kyubey is already helping out with grief seed management to some extent, so as long as we're on this plane it won't be as large of an issue. He's very unlikely to let us die or spiral out if we use the wish to control him, but even without that we're a strong magical girl and he seems to want to keep those around for a while for PR, so the risk isn't that huge. Plus Azura is a really strong teammate, and would be more helpful to us as a Magi then not.
(OOC reason is that Alivaril seems to like the idea of friendly Kyubes but that's not much of a justification to be honest.)