Outside of WWDC (which isn't even in person anymore) Apple doesn't seem to allow its technical staff to have much public visibility. On the other hand, the decline in visibility you cite might also correspond somewhat with a media shift toward the web and social media. I expect Apple has strict requirements regarding employee blogs and social media presence.

It's a shame, because Apple has great technical and design staff, and it would be nice to hear more from them.

But of course Apple is also a much larger company now than it was in the 1980s-2000s.