Eh? I find renko's defensive stats scale reasonably enough via skillpoints. Yeah maybe she's not a proper tank, but she can take a hit or two in slot two if you don't neglect her defense completely. Even a steel slasher. But yeah, don't need offensive skillpoints at all. Or offensive items. Really though, I do the same thing with kaggy. Yeah her mag growth is good, yeah defense ignoring attacks are good...But there are like a dozen characters with really good attack formulas on high attack stats, and there's only a few fights where defense IGNORE is truly more important than say, just a really big hit like Nitori, yuugi, youmu, patchy, etc. So basically, I just find she's still perfectly great if you focus on her being a buddha's stone bowl bot, and pour the vast majority of her skillpoints into mnd/spd. I mean I know she's good as a nuke too, but other than yukari, there really isn't anybody else who can replace the bowl (and even then yukari's eats up her sp much faster, plus the delay on it is brutal).
But anyway, it is indeed pretty cool to have a few characters with no need for any offensive stats (or at least little), it really makes you be able to have really powerful items that truly compliment each character perfectly much better. Not to mention allows you to make your entire party mostly status immune (though the actual stat debuff one tends to be a tough one to reach naturally, qq).
