I like coasters, and Disney's coasters especially, but I would absolutely still go to a coaster-free WDW.
Apart from theming, one key way to give a coaster "more" is to build it within a naturally dramatic scenic backdrop, like on a hillside (in my personal recollection, Busch Gardens Williamsburg and particularly Dollywood are good about this). It then becomes a kinetic form of landscape architecture, a way of experiencing that space that you could never replicate in any other way or in any other place.
Central Florida doesn't really have topography, except to the extent that lagoons count (IoA's is a huge part of why both Hulk and Velocicoaster are great)...but that has its limitations, as lagoons are even flatter than parking lots. Disney gets around this by building their own "mountains," which we admire all the more for being manmade.
Space Mountain is only a mountain in a strange abstract sense, but even with half a century of obvious popularity as measured in wait time, it may be one of the more under-appreciated imagineering achievements, because it's such a simple and effective concept. And the whole package is so cool aesthetically. I'd still rather wait 40 minutes inside that building than anywhere else in town, except maybe Gringotts or Everest.
Big Thunder is great. I'd rather have the Western River Expedition, but BTMR is a heck of a lot better than the superfluous mine train in Fantasyland that people seem to want to waste an hour of their MK day waiting for. The way it relates to the Rivers of America is really well done and provides visual interest in both directions. Also I'm addicted to the hats-and-glasses spiel.
Yeah...7DMT I wanted to like, but I just don't get it. We'll see if the popularity lasts or if it's still just the newest thing that many visitors haven't done yet. I'm not rushing back into that line any time soon. The caverns have too much redundancy with BTMR. I do like the view of the movie's beloved cottage dancing scene in animatronic form. Still, Scary Adventures was better.
I haven't ridden the Toontown kiddie coaster in forever. Such attractions deliver a lousy return on your wait-time investment but have an important place as a rite of passage to initiate future coaster fiends.
Slinky Dog Dash, also a kiddie coaster, is surprisingly not bad, but it's another 5000-minute average wait...in a queue that can feel a bit Six-Flags-ish. I can get why Toy Story Land with its toy-scale conceit had to be kind of treeless theme-wise (and to a lesser extent Galaxy's Edge; why not set it on a forest planet?), but Studios badly needs more shade everywhere. This matters, especially in Florida. Lush foliage is a major advantage of AK, parts of MK, and several of the better WDW resorts. Brutal sunshine is also a reason EPCOT Center needed to rely on an abundance of long, slow indoor rides. Orlando needs to re-learn how to love those. Thrill rides are great, but they last 2 minutes and then it's back to hoofing it around a hot park.
RNRC still has that great launch, but for me the whole experience is more of a campy Y2K nostalgia play than anything: a happy era when I visited the parks a lot as a teen during the Millennium Celebration with my parents and sister.
Talking about Everest makes me feel like a bit of a party pooper. I know everyone loves it, but to me it's simultaneously both over- and under-done. Love the queue, love the rockwork, somehow want the coaster to be either more or less extreme. A working Yeti would go a long way, and so would some general plussing once you're actually on the ride. It all looks like a zillion dollars, and yet it bores me a bit. Most of the great weird little details are in the queue, not in and around the mountain itself like they are with Big Thunder. It's so much like a more sophisticated east coast version of the Matterhorn, only I'm not sure they really improved on the original that much.
The Dino-Rama coaster is valuable only as a reminder of why Space Mountain is brilliant and had to be created.
Even if EPCOT needed a roller coaster (I'd be fine without it, but I think it's a fair argument that every theme park ought to have at least one), it should have been in World Showcase which after 40 years is about to get its 3rd ride...not some superhero thing in a giant cube overshadowing Spaceship Earth. Yuck.
Coasters are one necessary ingredient to spice up a Disney theme park, but they can't and shouldn't be the whole point of a park in Orlando, the way they are at a pure "coaster collection" like Cedar Point.
As I mentioned, I love Hulk and Velocicoaster (as well as Gringotts and Hagrid), but I'm with the previous poster on Rip Ride Rock-It: that might be the worst coaster in town. Hate it. Hate everything about it, from the lack of theming to the uncomfortable 90-degree lift to the obnoxious soundtrack(s). Not sure I ever did the Woody Woodpecker kiddie coaster or Pteranodon Flyers. Sea World it's just been too long to remember.
Finally, I always assumed that teens and young adults were the target roller-coaster audience for primarily psychological reasons (thrill-seeking behavior being a hallmark of adolescence), but as I've grown into my late 30s, I've increasingly appreciated why else older people don't love them: I simply can't enjoy them as much physically. Every aspect of my constitution, from inner ear to flesh and bone, has gradually grown just a little less forgiving and a little more vulnerable to discomfort. (And it doesn't help if I was drinking around World Showcase the previous night!)