Two things, was it something that needed to get done in the next 45 minutes? If not then a meeting is a big hammer for a small problem. If it only took 10 mins spread out over the course of several weeks it is still a time savings.

Second sure the discussion part could have been dealt with in a 45 minute meeting but how long did the thinking part take? Perhaps someone tested a few theories before presenting what they thought was the best approach in a short email. You aren't going to do that in a meeting you either end up taking the path of least resistance or you end up in another meeting after everyone has had a chance to go think and try stuff out.