Now see, I already KNOW how Rolemaster "explains" it.
Rather than Parroting what the Books say, I am saying I disagree with it. I don't see this in the works of Tolkien as the Elves are described.
In those books, The Silmarillion especially, you don't hear about the Great an Many unfinished works of the elves.
The Fact is you actually read the Opposite, you read about the Many great and wondrous things they did Create the structures and edifices they created.
The Argument that they are ultimate procrastinators, from my view point of the reading of Tolkien's works, fall short and incorrect in my view.
My reading.understanding of it is more that they don't feel the need to rush a work because they do have the time to get it done and get it done right.
It is the Humans who rush about trying to get thing done quickly and experience everything NOW, showing little Self discipline or control over ones self or ones emotions, irregardless of the consequences, because if they don't get it done now, they might not ever finish due to their short life spans.
A Few Dictionary Definitions of "Self Discipline"
self-dis·ci·pline
noun
noun: self-discipline
the ability to control one's feelings and overcome one's weaknesses; the ability to pursue what one thinks is right despite temptations to abandon it.
self–dis·ci·pline
noun \-ˈdi-sə-plən\
: the ability to make yourself do things that should be done
: correction or regulation of oneself for the sake of improvement
Synonyms
continence, restraint, self-command, self-containment, self-control, self-discipline, self-government, self-mastery, self-possession, self-restraint, willpower
Now How Rolemaster Defined "Self Discipline"
Self Discipline (SD)- The Control of Mind over Body, the ability to push harder in pursuit of some goal, or draw upon the inner reserves of strength inherent in any individual. Also referred to as: will, alignment, faith, mental strength or power, concentration, self control, determination, zeal, etc.
Now you may notices that the two Definitions, Real world and Game mechanic, don't actually Mesh. Especially when it comes to defining synonyms.
This, I believe is part of the Problem with the defining of stat bonuses with elves.
On the one hand, yes Elves have Ultimate patients... they can wait in the woods hiding unseen and unmoving for hours or even days, thus their great ability to Stalk and hide, and Get a Meditation bonus because they can sit for months contemplating the same subject. They have great control over their desires and emotions, seeing the humans as erratic, over emotional and, Shall we say, ADHD.
Elves are seen having great "continence, restraint, self-command, self-containment, self-control, self-discipline, self-government, self-mastery, self-possession, self-restraint, willpower"
They see the Humans as the ones who are weak minded and easily Manipulated.
If we go by the RM definition and synonyms: "will, alignment, faith, mental strength or power, concentration, self control, determination, zeal"
Elves Do have great will, Mental strength and power, concentration, self control.
perhaps they didn't have a lot of Determination, sure... the Zeal or Zealousness could be argued either way.
I think RM tried to much to Redefine what Self discipline means to where "their" idea of it didn't mesh. Especially when they applied it to Skills, it didn't mesh with the Tolkien concept of elves... so they tried to fix this with reverse bonuses/penalties to elves. Rather than fixing their definition of "Self Discipline" to what Self Discipline really is and excepting the fact that Elves Do have it.
Motivation is what they are truly speaking of Elves Lacking. And, IMO, Motivation isn't what Self Discipline was about.
Nor do I think Elves Lacked Motivation. They just had different Priorities with their Motivation than that of Humans, AS, due to their long life spans, they had a different, dare I say Broader perspective, of life and what might be important. ( not necessarily what is important ).