Ok, as a preface I'm not telling you how or why thru hiking is a thing. HYOH etc etc i'm not gatekeeping.
The appeal of thruhiking to me over normal hiking trips is that a thru is about self sufficiency, getting out there and having an objective. I do a lot of extended weekend trips that are like "hey lets all take friday and monday off and go spend 4 days out in the rugged mountains. Those kind of trips are awesome, and a lot of fun, but a thruhike is fundamentally different.
You're going to go out into the woods and start taking a colossal journey one perfectly ordinary step at a time. Escape from normal life and be out in nature amongst other goons just enjoying the trail and knowing you're going to be out there marching along your journey for a long time.
A thru hike is an adventure, you're setting out to accomplish something rad and confronting a part of yourself. Different people learn different shit from adventures and self discovery. Maybe your lovely wife would end up confronting her innate fear or rather need for clean comfort. I'm sure shes tough enough to sleep on an air mattress in an enclosed shelter, which means it's just why doesn't she want to? The answer at first would probably be something along the lines of "because I'm not a barbarian and I like soft sheets". But really, were humans, humans genetically used to live in caves and teepees. Nature and getting dirty is in our blood my friend. I think eventually the realization would be that aversion to camping out and getting dirty, is because it's outside of ones comfort zone.
Humans are robust, most able bodied people don't actually need the comforts of home to survive. Getting used to being out in the sticks, being dirty, and stinky, and not giving a shit as you continue on your adventure is, at least to me, the essence of the trail. If that long journey of marching and self discovery isn't what you're searching for and you want to stay clean, comfortable, and just get out and enjoy the rugged beauty of nature and pleasure of exercise then there are better choices of trails than a 2200 mile long one.