I didn't post that, I left my account signed in on my computer...
The real reasons are as follow. Shakespeare presents him as virtuous in Act 1 Sc 4 by using natural imagery in his speech;
I have begun to plant thee, and will labour
To make thee full of growing (29)
With this use of imagery, Shakespeare is saying that Duncan's position of power in the hierachy is akin to the natural order of things. This is emphasized by the level of humility which his subjects show him:
The service and the loyalty I owe,
In doing it, pays itself... (23)
Also, the natural lines which Duncan uses also imply that he is intending to reward Macbeth and his subjects further. Especially because he has only just "begun" to "Make [them] full of growing".
It is also shown by Shakespeare that Duncan values loyalty greatly in the same Act, through the lines;
He was a gentleman on whom I built
An absolute trust (15)
In these lines, Duncan is rejecting Malcolm's praise of the previous Thane of Cawdor's 'honourable death' by saying that repentance is less important than the integrity of loyalty.
he had a good sense of style. like david gilbdrfrt