(Note: This is the first part in the series of entries relating why I like the idols I do and maybe thingking about why other people like their favorite idols. If you want more info check out the posts all labeled What I Like About My Idols)
(Also note that if I mention Ishikawa Rika too much, I'm not trying to be annoying or get you to like her; she's just my favorite idol by a LONG shot, and so when I think about examples of things like this my mind goes to her.)
OK, so I'm sure there's some smart ass who reads the title of the blog post and will think "Oh, her favorite idol is Ishikawa Rika, of COURSE she's just going to say that vocal ability is unimportant." Well, um, you're partially right. (though I do think that Rika's underestimated as a singer, but that's a different topic). As a whole, when judging which idol in a group is my favorite, I really don't care about vocal ability. Even when talking about my #2 favorite idol of all time, Matsuura Aya, who's often lauded for her vocal abilities, that's usually a few things down the list, and I don't just say "I like her voice."
However, this isn't to say that vocals aren't important or aren't a good feature that draws people (including me) in when first discovering an idol. I remember discovering that I really liked Ayaya when I kept hearing about how amazing that she was and when I agreed with them I immediately wanted to watch more of her performances and more of her. However, on the flipside there are certain idols I'm sure I'd be much more tolerant of if I actually could tolerate their voices (I don't want to be killed by angry wota so I'll leave it at that). However, it's not always vocal skill but more of "is their voice listenable to me and do I like the tone?" with the one exception of mine being Ayaya.
In fact, often I think that being an idol with stronger vocals might make it a bit more difficult to be, well, idolly. One of the things that wota like about idols and that I like to a certain degree is the idea that one must support and cheer on their favorite idol (which I think is part of what makes wotagei so popular; idols literally hear a fan's support). It's almost easier to support the underdog of the girl with decent vocals but not great vocals. It's almost as if you start with
something (in this case someone, an idol) that is unpolished, it's easier to feel proud of cheering that person on and feel pride in their successes.
I manifested that when I posted a small post with a Youtube clip of Rika singing, that I posted mainly because I was proud of her. With most idols (again, with the exception of Ayaya who never ceases to amaze me with her talent) if you have one who's always good, it's a bit harder to cheer them on and feel pride like you do with the others. An example of this is if you were a fan of Suzuki Airi, it'd be more of "wow, Airi sounds really good. Like last time" as opposed to a fan of Nakajima Saki being able to go "wow, Nakky has improved so much in the past year!" It's personal preference, and the way that I feel idol fans can be, but sometimes a singer being too good (though not Aya level XD) can make it harder for me to support them.
However, when push comes to shove, vocal skills can bring me in or push me away, but they are in no way anything that makes me love or hate an idol. A good song with good vocals will pique my interest, but it's really up to the girl(s) to keep my interest.