[MENTION=6787650]Hemlock[/MENTION], after your post about OSR/AD&D style incentives, I'm curious - have you adjusted your approach to 5e, or houseruled anything, to deal with some of the issues being discussed in this thread?
Yes, although I continue to experiment further. For example, I haven't yet implemented Courtney Campbell's insights about "traditional" directed-acyclic-graph style adventures. My natural style is wide-open sandbox but I'm experimenting with imposing more structure, for the sake of the players, without wanting to go all the way to a linear structure. I may do the DAG thing this Wednesday though.
But so far, I've increased XP requirements in my new campaign by factor of 10x (with my players' full enthusiastic agreement) and started handing out XP for gold on a 1:1 basis for gold spent offscreen in certain predetermined ways (sending gold home to your home village; buying presents for your love interest). The new campaign is still pretty new, only a few weeks, so the only definite feedback I have so far is that one of the players expressed gratification at the fact that, at the end of the second session, he was still at first level despite having earned close to 3000 XP. I
think it's working but I'm not sure. We did have a discussion at the end of session #2 where one of the players felt like they were earning so little XP from goblins that it cheapened the play for him, but we fixed that by adjusting the rules. (They wound up getting 50 XP per goblin instead of 13--the new rule is that you shift monster CRs by 2 categories before applying the monster CR

layer level ratio, so a 1st level PC gains full XP from a goblin.)
I think my next move is to see if I can apply these new house rules to construct an adventuring day full of weak foes without breaking my own suspension of disbelief. Probably it will be something like:
(1) PCs approach orc village (they've already expressed an interest in going there).
(2) An orc "tough" picks a fight with one of the PCs while his gang looks on. Presumably they flatten him; otherwise he goes through their pockets and leaves them for dead, laughing with his buddies.
(3) An agent of the current orc headman (female?) shows up, patches up the PCs if necessary (Healer feat) to demonstrate goodwill, and asks them to come meet secretly with the headman.
(4) Headman outlines current troubles w/ kidnapped elders (I'm going to go for the Quill of Law approach here) and an ongoing coup attempt, asks for help. Unfortunately he cannot help at all since he's already read the laws in question and must therefore obey them--but the PCs have never read the laws and so are not bound by them! (PCs must be careful not to read any signs or proclamations now.) They get to negotiate a price with him for their help, and he signs a Contract of Nepthas with them to enforce it.
(5) Six or eight encounters with orcs follow. The PCs hopefully liberate the elders.
(6) Twist: there's a loophole in the contract they signed, if they didn't detect it in step #4. They may need to threaten the headman to get paid, or make a brilliant legal argument, or just grab the treasure and run. Or maybe the headman likes them enough that he pays them anyway, despite the loophole.
(7) Hopefully, they get a bunch of treasure and need to get out of town quick.
(8) Bandits attempt to follow and intercept them when they camp for the night and demand a share of the treasure recovered from the filthy orcs. Can be evaded via stealth.
That's my basic outline, but I need to work on it for a bit to give it more choice points and make it less linear/homogenous. Maybe vary the terrains in which the elders are being held, make some of them guarded by worgs and others by orcs, add some wandering monsters (thug patrols), orcs with different weapon types, and a reaction squad of six orcs on horses who will come when called via gong. Maybe add some disguises and spycraft.
Steps #6-8 seem likely to occur on a different "adventuring day" than #1-5.