DisneySea is a park that AK is often compared to, but having been to both it's unjustified IMO.
DisneySea currently has 21 rides. That includes 9 major attractions, plus a dozen kiddie/flat and transportation rides to round out the mix. This ensures that everyone, regardless of their age or physical limitations, has enough to do to fill the day. This count does not include other types of attractions or theater shows, which DisneySea also has, or the 4 rides currently being built for Fantasy Springs.
AK has only 9 rides, and most are thrill attractions and/or have a height requirement. That means many guests are not able to enjoy them, which limits the number of experiences they can do in a day. This is why regional parks are starting to move away from mega coasters, because the % of guests who actually want to do them is quite small. DHS also suffers from this same problem, and coincidentally also has just 9 rides, despite all the recent money spent.
The EPCOT pavilions in their heyday, were much longer experiences. World of Motion, Horizons, Imagination and Energy have all been replaced by shorter rides, some of which now come with physical restrictions. EPCOT Center in 1989 had at least 11 rides, which is more than what either DHS or AK do now, and almost all were accessible to guests of any age.
Parks like Euro Disneyland and DisneySea have an enormous amount of detail and areas to explore, but that detail was not sacrificed for capacity or variety of experiences. Animal Kingdom was because of budget constraints and has never really reached its potential in that regard. A good park has both, not one or the other. That's why people are much more likely to think of MK as a "full day" park, despite being significantly smaller than AK.
Rides are the bread and butter of the theme park experience, and Disney attractions need to appeal to a wide audience. Exhibits and shows and nice, but they are often overlooked or not well advertised. AK needs more family rides.