They're not genuinely excited. Because there isn't much to be genuinely excited about. The "incredible new super-exciting developments" are usually "okay, I guess."

Once in a while you get something like the M series chips, but the rest is reliably mid - functional, maybe a few nice tweaks, probably some better-than-average design, but nothing revolutionary.

So all of the "We know you're gonna love it!" doesn't land, because it's literally scripted and rehearsed, not spontaneous.

Jobs was rehearsed and passionate, which was part of the appeal.

It's debatable if Cook has ever been genuinely excited about anything.