I understand the backdoor shortcut in Skyrim since it's all open-world with no "levels" or cutscenes, but in a pen-and-paper game the DM can just "yada-yada" the multi-hour uneventful walk back to the entrance of the now-cleared dungeon.
If, as the DM, you're letting your players trek unimpeded and unchallenged back to the relative safety of civilization after looting a hoard dry, those players will never understand why murderhobos are the worst.
To put a finer point on it: next time your players're heading out on an adventure, have them cross paths with a clearly depleted group overburdened with treasure and magic trinkets making their way back to town... Do your players stand aside and wish them safe passage or, do they choose the efficiency of quick & easy cash over deadly risk over yonder horizon?
Au contrare, sir or madam. I'm all for "shortcuts" as they're quite simply an illusory sigh of relief. Let them take the elevator up after all's said and done — even let them anticipate doing so as they begin the final showdown, et al.
See the hope in their eyes as they hang future plans on that gleaming shaft of transit tech, listen to them enmesh it in their exit strategies, (complete with skill-checking on the various buttons and backslapping each other when whatever they did made it work suddenly) and watch it evaporate as the chime sounds and the doors whoosh open on an array of fresh troops heading down to work...
This is that slo-mo second when they find out it's the same elevator the site's reinforcements were about to use when the heroes happened to be coming up with the exact opposite of intentions. 😜
To be fair, I'd be pretty damn skeptical of something that easy. There's always a catch, and I'd bet dollarydoos to hexed donuts that someone in the party arriving at said inn is no longer precisely who they were going into the portal.