However, Nagai also has a lot of issues as a director. The terrible pacing of To Aru Kagaku no Railgun has a lot to do with poor directing decisions. Idolm@ster Xenoglossia also has a number of issues which can be attributed to Nagai. What’s more, amongst his good work, Toradora shines a lot brighter. I like Kaitou Tenshi Twin Angel, and his directing flair has a lot to do with it, but it doesn’t include the subtleties you are mentioning here.
Whoa, whoa, whoa. Let’s not get too sidetracked, lest we lose sight of what I was talking about originally. I bolded the anime names in that quote for emphasis—those series are all action-based, or at the very least with a strong action/battle element to it.
Apples and oranges? I think so. I’ve only seen Railgun out of the three that you mentioned, but it was definitely heads above Index for the sole reason that I actually cared about the characters. Toradora is not an action series, it’s a high school love comedy affair, and you can’t be telling me that you’re comparing the work Nagai’s done with action-centred anime with the work he’s done with relationship-centred anime, are you?
It doesn’t make sense to compare him to Taniguchi Goro, because Goro has a lot more to do with what goes into his works.
I should clarify: it was an analogy, i.e. Nagai isn’t literally Taniguchi in the sense that they produce the same level of entertainment in their action anime; rather, he’s akin to what Taniguchi is. If Taniguchi gets off on using an elaborate, outlandish plot to manipulate the viewer, then so does Nagai do the same with relationships. Taniguchi has an eye for the big picture, but Nagai goes micro and focuses on the intricate ways in which characters interact with each other.
As for your last point, I’ll get around to reading the Toradora novels after I’m done with the anime, so we’ll see about that one later.