I'm not sure it's so much a matter of how the park is originally designed (though I'd be curious to hear any specific design traits you have in mind). I think it's a matter of what type and scale of attractions get green-lit in the modern era. Nowadays every attraction has to be fairly substantial to get the go-ahead, and maybe that's because nowadays a new attraction opening is designed to provide a more impactful marketing "moment" and bump than back in the day.
Compact (acreage-wise), attractions like Swiss Family/Adventureland Treehouse, Sleeping Beauty Castle walk-through, Fantasyland dark rides, Enchanted Tiki Room, Country Bears, etc. don't seem to happen as much nowadays. But if Universal wanted to, they could tuck a bunch of small attractions here and there all over the park. Between queuing and the experience, each may only occupy a guest for 10-30 minutes (shorter for the walkthroughs, longer for a compact dark ride or show), but adding ten of these could fill up several hours of a guest's day...and take some pressure off the E-tickets by providing an alternative.
I'm a big endorser of these types of attractions, so I hope Epic is packed tighter in the years -- or more realistically, decades -- ahead.