> life-drawing is a practice that is good training for a specific use of that tool - portraiture

> The question is, why did they continue for so long?

Well, as said in the original quote, it's apparently also good for internalizing a sense of weight for animation. So presumably they continued at least in part because it's good for things that aren't as obsolete as portraiture -- animation isn't the only way to make money in art these days, but it's not exactly in low demand.

I'd wonder why they dropped it, but at a guess, it's some combination of low demand (first they make it non-required, then students who don't realize the broader applicability stop taking it) and higher cost (you need to hire one or more models).