Why can't Dungeons be longer/harder, but more... piecework?

[testname]

Coz dungeons are boring.

Make it fast, get tomes, end of story.

[Shurrikhan]

Coz dungeons are boring.

Make it fast, get tomes, end of story.

Then...

1. What about making dungeons... not boring?
   
   
2. Why do something so boring at all? Alternatively, why should that particular task be necessary, if there are more enjoyable ways we would otherwise be able to get those rewards? Why should something so dull be made the most efficient method of collecting tomes (which are initially necessary for progression)?
   
   
3. [Hypothetical] If one were to take issue with dungeons' being so dull, why would they then -- even if, admittedly, among many others -- conditioning development towards more of the same by requesting efficiency over enjoyment ('give me something unpleasant, but quick, so I can more quickly get to the thing I'll try to make as quick as possible, even if I make it proportionately more unpleasant in the process')?