This question came up on the WDW Today Facebook group, and I think it is a neat one to look at in depth. The question was about why there is no walking trail to get from Animal Kingdom Lodge to Animal Kingdom park. Certainly, Disney sends mixed messages when it comes to walking from hotels to parks. You can walk from the Contemporary and Bay Lake Tower to the Magic Kingdom, but you can only get to the Ticket and Transportation Center from the other two Magic Kingdom monorail loop resorts (Grand Floridian and Polynesian). You can walk to both Epcot and Disney's Hollywood Studios from the Yacht and Beach Clubs, Boardwalk, Swan, and Dolphin hotels.
Jambo House and Kidani Village are about a mile to a mile and a half from the front entrance of Animal Kingdom, and would be a viable walk for those inclined. Certainly on a typical trip, we walk 10 miles or more in an average day, so what's one more? There is a walking path between Jambo House and Kidani Village, but no way to walk (safely, that is) between Jambo House and Animal Kingdom.
Looking at an aerial view through Google Maps, the most direct path would be to draw a line from the back of Jambo House to the bus stops at Animal Kingdom. There's a few problems with this, however. The first is that the savannah at the back of Jambo House (the one you see from your room) is in the way of this ideal walking path. If that obstacle was overcome, you would be walking past what appears to be a paddock facility for the animals. (As you are driving into the Lodge, it's that first turnoff from Osceola parkway that so many people take by mistake.) In addition to the stress it might cause the animals that are in need of isolation to have people walking through there, it's isn't the most lovely scenery to see as you walk through.
If you managed to get past that, you now have a large swath of forest to go through. If this is not an outright conservation/protected area, which would mean it couldn't be bulldozed for a sidewalk, it provides a necessary buffer between the theme park and the hotel. Living about the same distance as the crow flies from I-95 with just forest between our home and that busy bit of road, I can tell you that those trees provide a very needed noise barrier. In the summer, when there's leaves on the trees, we can barely hear I-95. In the winter, when the leaves are gone, we hear the traffic with great ease. Even tearing down a small area to put in a sidewalk could contribute to noise issues.
This also becomes a safety issue. You would have a lightly traveled walkway surrounded on both sides by trees, and lots of tourists, presumably carrying cash and electronics, on that path. Perhaps it is just the viewpoint of someone who lives up in a metro area where people are snatched from walking paths and pulled into the woods on a frequent enough basis, but that seems like a place that could be a major safety concern.
Once you get past that, Black Lake is in your way. That would mean rerouting pedestrians onto Black Lake Road, which is a road used by cast members. While many, many cast members are responsible drivers on property, there are some that are not--and this could be a potential safety hazard, especially when you get to the corner of West Savannah Circle and Black Lake Road. Suddenly, you have to make sure those pedestrians are safe when crossing the road. Having watched people suddenly lose their understanding of what a "Don't Walk" sign means when they are on vacation around the Contemporary, there's potential for safety issues there as well. Once they are past that, they would walk around the bus loop and into the park.
The other alternative, which is more realistic, would be to have everyone walk out to the driveway for Jambo House, head down Osceola Parkway (crossing the driveway into the maintenance area at Animal Kingdom Lodge and then crossing Black Lake Road), going in the exit of the parking lot and walking the entire length of the parking lot to get to the front entrance. Watching how people tend to drive on Osceola Parkway, I'm not sure how comfortable people would feel, even on the sidewalk.
Doing a little Google-fu, it apparently costs between $1 million and $2 million per mile of sidewalk to get it installed when you take into account making adjustments for modifying right-of-way and redoing drainage systems to accommodate the sidewalk. It then becomes an issue of whether that money would benefit a large number of people. Although many people at Disney are not opposed to walking, over the years it does seem that fewer people want to walk long distances without a good reason. Without trees put in to provide shade, this would be a very hot walk for large portions of the year, and putting in and maintaining trees would be expensive.
In the end, I'm not so sure this is a case of "If you build it, they will come." Judging by how few people use the very short walk between Kidani and Jambo when they go to or from their dining reservations (and I am guilty of that as well), I'm not sure that a walkway would get sufficient foot traffic to justify the initial cost and maintenance fees. Make no mistake, I'm a huge fan of walking between hotels and theme parks whenever possible--and because of that, if I think that as an avid walker and my husband as a runner would not be likely to use that path, it probably wouldn't get much support from the greater Disney resort guest.