The Unabridged version
I think a lot of it is the romance and history. You are also buying a legacy when you buy a LR. But there are other reasons; Rovers are VERY capable out of the box. It's true the years the Disco's came without a CDL they were significantly hindered, but by in large they are pretty impressive. More than a couple of times I have reached the peak of a trail in my bone stock Disco and met up with people who were floored a stock truck was able to negotiate such terrain. Many times I have gone around lifted pickups and motorcycles were not able to compelete a difficult portion of trail only to motor up it with one hand on the wheel, a drink in the drink holder and climate control pumping out a steady 70 degrees - stock. You also get the articulation and ride of coil springs, something leaf springs can't really match without making compromises.
There is also the build of the vehicle. Look under one sometime. The only things I see that are built like a Rover are LC's and trains. Just the radius arms alone are impressive as is the factory guard behind the factory plastic airdam. I bounced my airdam off a tree stump buried in mud hard enough to lift my front end up. I honestly thought I was going to be bringing my bumper home on my roof rack. But, because LR over builds their products to such a high degree, there was only a couple light scratches to show for it. What other manufacture reinforces the plastic under the bumper so much that you can lift the vehicle by it (Wow, you're still reading this?!?) without destroying anything?
There is also a ton of small things like the air intake. It draws from in between the inner and outer front fender above the height of the headlight. The real fording depth of a Rover is very deep (as long as you keep your bow wake and don't stop). I've been able to reach out of my window and touch the water with a bow wave that continuiously crested my hood without any problems. Or those wonderful rain gutters that not only allow you to put obscene amounts of weight over your head, but also let you drive with the windows half open in all but the most severe rain storms.
Disco's also have a great wheelbase for off-road. I love Toyotas and all but Tacos, 4Runners, and LC just can't turn like a Disco. The short wheel base also gives you some help with your breakover angle. D110's are not as agile, but clearance is great regardless and the fact that they are bolted together, not welded makes them pretty much indestructable.
Space is a nice benifit too. My personal preferences is an SUV for off road. I like having everything inside and within reach. With a pickup you either have to leave your gear exposed in an open bed, or put a cap on and work around it when trying to retreive things at the front.
Finally, there is the interior. Rover's aren't fancy, but they are nice. D110's are all busniess. Well-built and very functional interiors with TONS of storage space that won't destroy all of your belongings with a harsh ride. Need to screw or bolt something into the interior? Easy - you don't have to start pulling pannels off and figure a way to mount something without ruining your interior. Discos have a lot of room too, but they are also very well done. My wife has a 2006 BMW and, while the Disco isn't quite as nice, the quality feels just as good. Nothing rattles and fit and finish are great. The plastic isn't quite as good as the BMW, but it is better than my Toyota. I don't think anyone spent a whole lot of time on ergonomics (what's up with the interior door handle placement on a Disco??), but what are you going to do.
Ultimately, it comes to this for me, there are only three vehicles that I can think of that feel like a luxury car on the highway and can keep up with Jeeps off road: Land Rovers, G-wagens, and LC's (who really uses G-Wagens off road anyway). I love LC's - I very much want one, but they are just a little big for me.
Besides, they are pretty reliable. Yes, they require more upkeep than pretty much anything else. But, if you do it, you will have a reliable luxury truck that can take on most trails bone stock. Bill Burke has a D90 over 150K as one of his guide trucks. He makes his living taking people into the backcountry and does it with a 150,000 mile Rover - they can't be that unreliable.
And don't even get my started on the LR3's. Yeah they are too complex, but they can outperform pretty much everything except maybe a Rubicon off road.
All that being said, I think it is a total person choice. I'm not saying LR is the best, but there certainly are good reasons they have such a loyal following in the off-road community.
Ow - writers cramp!