I have honestly never looked at this issue the way you lay it out in your previous post, Hound 109, and I will admit it made me go 'hmmm...' But in the end, I think the major point for most people is; at WDW it
makes sense to stay on-site, there is added benefit in
comparison to staying offsite.
1. The size and lay-out of WDW demands that you cannot walk, no matter where you stay, to all of the parks. Alternative transportation is a must, so for many, it is not a factor to consider at WDW...you have to drive or bus where ever you stay! With DL, you can walk, often quite quickly, to and from the parks. Now, it is my understanding that the walk from some of the on-sites there can actually exceed the walk from the hotels across the street...for many, that is a swaying factor.
2. At WDW, you can have your packages sent to your hotel as a resort guest. Not the case at DLR, unless I am mistaken. For my DH, who often leaves the park looking like a pack-mule, this perk alone is worth staying on-site in WDW. In DLR, storing items in a locker and then packing them the short distance across the street is not a biggy.
3. The larger majority of people who visit either resort, although granted maybe not the majority of DISr's, are looking for the best value they can get. That is the reason WDW offers more Mod/Bud resorts than deluxe. The less expensive places to stay on Harbor do fill that void. A lot of people are simply going to assume coming from WDW, that a hotel that is on-site at DLR is going to be closer to the parks and have nicer ammeties, because that is a fact in WDW. It is not so at DLR, and I think that is most people's point here on DIS when we say...it may not be worth the extra money to stay on-site.
4. The immersion factor: I think this is a little over-thought myself.

I mean, really, everything in the whole area is devoted to Disney. The hotel lobbies all give nods, if not monuments, to the mouse. The windows give views of
Disneyland, that alone immerses you in the mood of Disney! All the people coming and going, wearing ears and matching Disney T's, the billboards and music, and at night the boom of fireworks...I just think the whole area is a wonderful immersion, there is no 'hierarchy experience' by being within DLR hotel walls.
So, if someone has the extra money and wants to be very close and have the best deluxe amenities, then by all means, on-site at DLR works for them. But I still stand by my statement that it doesn't make as much
sense as it does in WDW.