Even so, attack powers using a secondary stat would be anywhere from 1 to 3 points below a primary, so it's usually a poor choice.
1 point below is not a poor choice.
The poor choice is either multiclassing or hybriding in the first place. Yeah, someone can sometimes get a minor cool effect or ability and there are a few builds that actually work semi-ok, but both of these concepts just plain suck and are not well thought out.
Want to be a Fighter / Wizard? Guess what? You're in luck. We put out the Swordmage class just for you!!! Whatever.

If WotC would have designed good multiclassing rules, they would only need 12 classes and they would have 156 (or even more with multiclassing into a third class) class options, all of them viable.