True, if humans don't have goals, they tend to feel lost / bored.
The rest of the post, I'd kindly ask that you back it up with logic. The "more you think about it" is not an argument that provides any objectionable evidence to the contrary. ^_^ Perhaps provide math, as it's extremely objectionable as long as it follows sound logic. I can also provide math, if it's requested and propose trajectories in leveling based off of my logic. Actually, I'll do that now!
Proposed Trajectory as it is, assumptions / baselines:
*Average of 15 XP / kill
*Monster count per dungeon: 20
*Average time in dungeon: 20 minutes / once a reset (when alone)
*Quest reward: 300
*Quests are locked to certain level ranges
*Higher PCs cannot come into quests for aid
*Higher PCs can come into exploration areas for aid
*Not counting DM quests / plots / XP
*Average tick of 15 XP / 15 minutes
Proposed Trajectory with minimum level, assumptions / baselines:
*Average of 15 XP / kill
*Monster count per dungeon: 20
*Average time in dungeon: 20 minutes / once a reset (when alone)
*Quest reward: 300
*Quests are locked to certain level ranges
*Higher PCs can come into quests for aid
*Higher PCs can come into exploration areas for aid
*Not counting DM quests / plots / XP
*Average tick of 15 XP / 15 minutes
Here are the formulas I used:
k = kill XP, m = monster count, a = quest reward, t = time to complete, c = XP tick
XP / min during dungeons/quests (remember, this is once a reset): ((15 <k> * 20 <m> + 300 <a>) / 20 <t>) + (15 <c> / 20) = 30.75 XP
XP / min during RP: (15 <c> / 15) = 1 XP
XP / min during exploration: (15 <k> / 2 <takes half the time to find monsters>) + (15 <c> / 20) = 8.25 XP
XP / min during higher explorations: (40 <k> / 2 <takes half the time to find monsters>) + (15 <c> / 20) = 20.75 XP
If you did 3 quests a day, no higher help, and played 5 hours a day only killing things:
Time per day = 300 minutes.
3 quests would total (30.75 * 20 min = 615) = 1845 XP. Take that from 300 minutes for 240 minutes. The rest would be 8.25 / minute = 1980 XP. The end of day, you'd have 3825 XP.
If we use level 9 to level 10 as a baseline, you need a total of 9,000 XP. Meaning you can level to level 10 in 3 days. This is the heart of the argument.
If you did all the quests a day, no higher help outside dungeons, and played 5 hours a day only killing things:
Time per day = 300 minutes.
15 quests would total (30.75 * 10 min = 615) = 9225 XP. Take that from 300 minutes for 150 minutes. The rest would be 8.25 / minute = 1980 XP. The end of day, you'd have 11205 XP.
If we use level 9 to level 10 as a baseline, you need a total of 9,000 XP. Meaning you can level to level 10 in 1 day with 2205 spillover.
If you did 3 quests a day, higher help during exploration only, and played 5 hours a day only killing things:
Time per day = 300 minutes.
3 quests would total (30.75 * 20 min = 615) = 1845 XP. Take that from 300 minutes for 240 minutes. The rest would be 20.75 / minute = 4980 XP. The end of day, you'd have 6825 XP.
If we use level 9 to level 10 as a baseline, you need a total of 9,000 XP. Meaning you can level to level 10 in 2 days. This is the heart of the argument.
If you did all the quests a day, higher help during exploration and dungeons, and played 5 hours a day only killing things:
Time per day = 300 minutes.
15 quests would total (30.75 * 10 min = 615) = 9225 XP. Take that from 300 minutes for 150 minutes. The rest would be 20.75 / minute = 3113 XP. The end of day, you'd have 12338 XP.
If we use level 9 to level 10 as a baseline, you need a total of 9,000 XP. Meaning you can level to level 10 in 1 day with 3338 spillover.
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With the math out of the way, I definitely see the concern (Also note the average of 15 XP / kill isn't even exactly what I've ran into - it's more like 8-10 for me). However I still would like to find a way to open up dungeons for explorations for PCs like Zazie or being able to go into a crypt for PCs like Teuivae. So here's my simple compromise to both parties:
TL;DR
Leave quests alone but allow players to enter the instances without requiring the quest to enter. The XP amount would be no different than exploration areas and without that sweet quest XP reward, the XP / min goes back down to exploration areas (or equal to dense exploration areas). This way the XP / minutes stays about the same as it is now but allows PCs to explore quest dungeons without quest rewards.
Just add a latch that says, "if PC has quest, only those with the same quest enter the same instance" to stop any sort of loop holes of higher PCs entering the same instance as a questing PC. A higher PC could still take them to an area to "train" and yet even have a reason IC to say, "you must do this quest on your own, prove to me that you've been paying attention".
(I spent 3,600 seconds on this, don't let it flop!)