I think this is mainly due to 2 (3?) reasons: the first being that there is always a lot of excitement for a new club, and people will tend to be interested/want to join. But it might also be that there is particular excitement to read a certain title, but not necessarily others - in this case it seems that ふしぎ is more popular than Kiki.
The other reason I’d say is basically that there are too many bookclub options in Natively. I’d surely like to join the next club, but there’s also the LN club, the beginner LN club, BL club, GL club, mystery club, wanikani book clubs… there’s no way to join all of those at the same time. So for this round at least, I’ll finish 魔女 and probably skip the next poll in favor of a different club.
I don’t think I voted this time or submitted any options for to be read, partly because I failed to finish ふしぎ駄菓子屋, partly because I haven’t had much time to support reading way above my level recently and partly because I have not managed to purchase books as easily as I could previously (it can take me 2-3 months to get books from my usual source now whereas before it was only 2 weeks and I don’t regularly put orders in on alternatives like CDJapan).
I would like to read Kiki but just can’t atm and don’t feel it was suitable for me to vote for things I’m not taking part in.
A few things are probably at play. ふしぎ駄菓子屋 ended with only 4 people active, so perhaps a lot of people who were initially interested and dropped out moved on to other natively levels or genre depending on why interest dropped off. That could be one reason the second book had many fewer voters.
As someone who really enjoyed the club and book - I’m actually still reading sequel volumes of ふしぎ駄菓子屋. So those alongside other clubs that are all longer series (4), I just ran out of time for adding another series or club. Maybe someday I’ll get the hang of reading one book or manga and stopping, lol, but I’m currently sucked into too many clubs and series to contemplate adding another one
and WK, there is simply more fun stuff to take part in than people to populate all the clubs. At some point when WK clubs were growing about 4-5 years ago, the collective leaders of the clubs put their heads together and seemed to avoid adding formal clubs from a certain point to avoid spreading readers too thin. Perhaps the same thing will happen here naturally, or another solution could be found.
I could imagine one solution might be that clubs that don’t have enough members to keep reading new books back to back, they could stagger their starts throughout the year. For example, maybe the children’s book club just runs once a year instead of 2-3 times, but there might be more participation when it does happen. Just an idea, maybe there are other solutions.
I’ve also enjoyed seeing people coming through and reading books after the club has finished up and regenerated some discussion in the book club threads. Even if we only have a few people with the club’s schedule, other people may read the books later and also engage in the discussions.
I was somehow trying to edit the nomination post into a poll, but it didn’t quite look right.
The original post says there are 5 votes, but your poll says choose up 3 options. And I’m not sure if it’s configured to be finished at Juli 21 (9 days of voting).
Looking at the poll, it kind of feels like there’s not enough interest at the moment. 8 voters in total, and the currently leading titles have 3 people each who want to read them…
Literally none of the top 3 are books I already own, which sucks. I just voted for one of the 3 there because I didn’t want either of those other ones to win.
Edit: I see now that someone changed/removed their votes so I’ve failed.
– I caught like ten minutes of the anime on late night Japanese TV when I was idly channel hopping, and it was a 
No idea how though, I wasn’t going to vote because I don’t have any of them and couldn’t get any in time.