History - What happened to King Robert I?

William Rufus was only the third son of William the Conqueror - yet he inherited England.  Why?  (Never mind that William's fourth son, Henry, eventually bagged the lot.)

In fact, William was said to have nine children.  His second son, Richard, died early (hunting, by the sounds of it - the key royal pastime of the era).  Of his five daughters, three also died early without issue, and one became a nun.  The fifth, Adela, had a son who was briefly King Stephen of England.

Oh yes, back to the kings of England.  When William the Conqueror died, he bequeathed Normandy to his oldest son Robert, and England to his next in line, William Rufus.

Why?

I've heard two contradictory reasons offered.

On the one hand, it is said that - for a number of reasons - William had an aversion to his oldest son, and was inclined to disinherit him, but was persuaded against it, instead giving him Normandy, while giving the younger William Rufus the better prize, England.  There were riches to be had by milking the people there.

On the other hand, these people are Normans, and preferred Normandy as a far more civilised land.  Where their loyalties were divided between the two lands, they frequently spent more time in Normandy than England.  And they spoke French.  Normandy was clearly the better prize; England was for the barbarians.

The alternative explanations are meaningful: the issue revolves around what the Normans valued.  I'm surprised that historians can't settle the question once and for all.

One could say that this issue of value affects the course of history for hundreds of years.  However, as it happens, Robert was not warrior-like enough to hold on to Normandy in that martial era.  Conversely, William Rufus was ruthless enough to hold on to England.  But in any case, by hook or by crook their younger brother Henry managed to bundle off both his brothers and snaffle the lot.  William Rufus died in a hunting accident - while Henry was in the area - and Robert, well, Henry imprisoned him for the last thirty years of his life.

You see, at the time it was being mean and aggressive that paid off, and there were spoils to be had for the victor.

But was Robert never king of England because he was the lesser favoured, or because England was the lesser favoured?