It can be correctly argued that DAK is NOT a half day park. If you want to do everything, it's actually more than a day given their short operating hours. But it's all based on personal preference.
These days, it would be difficult to argue that DHS can actually fill an entire day. The only way that can be said is if you see all the shows.....and only because the timing doesn't work out to see both stunt shows at convenient times, so you'd end up killing time between things.
MK is a multiple day park, hands down.
Epcot can be argued either way - again, it just depends on whether you enjoy meandering the countries, and seeing all the shows.
For ME, DAK is a "1/2 Day Park" simply because I'm just not into "animals" that much. We have a decent zoo here in Indy, and one visit there is enough animal exposure to satisfy me for a year.
DAK is a beautiful park, and I really enjoy the few major attractions (Safari, Dinosaur, Bugs Life - can't do EE because of motion sickness). But I'm also not a "show" person, in general. And I've always visited when it's hot, so walking the trails has been pretty much the worst thing in the world.
If I could visit when it's 70 degrees and breezy, I would have a vastly different opinion of the park. But with it being hotter than the other parks already, coupled with miserable Florida weather, it's just not a park I can enjoy.
DHS used to fill my day, but not anymore. A few headliner attractions and we're done. Before FP+ we could stretch the day out longer by getting multiple FPs for things like ToT (our favorite ride), but those days are over...so now we just leave after lunch. The hassle of Fantasmic isn't enough to keep us there, or bring us back.
We can make a day of Epcot. We'll finish FW in the morning, get lunch, and walk WS. We typically leave, refresh, and go back around dinner time, then hang out for Illuminations. So, not technically a full day of touring, but it consumes an entire day, whereas DHS and DAK do not.