Not to speak for HRE but I think what he's saying is not so much that Crosby doesn't have a strong leg, but that "strong leg" has been essentially redefined in the NFL by the modern kicker to the point where Crosby is just one among many.
As mentioned, Carpenter hit a 58 yarder with ease, has hit from 60 in the past, and you've got guys like Janikowski, Akers, Tucker, Bryant, Feely, Bironas, and Zuerlein hitting from 60+.
Even guys like Gould, Dawson, Barth, Nugent, Walsh, Gano, and Scobee have hit from 55+ in the last few years.
Granted, there's a difference in kicking in poor weather and kicking in a dome, and I'd be curious to see a study on how much of a difference in makes. But kickers like Gould and Carpenter, and even some of the ones out east, deal with it during the late fall and winter months as well.
It's just that a strong leg is an expectation of the modern kicker, to some extent. You don't see much more these days of the guy who is money inside 43 but can't be trusted from 50+. Both power and accuracy are an expectation of today's kicker, not one or the other. So it's not that Crosby doesn't have a powerful leg IMO, just that it's not a skillset that is unique to him by any means.