I have heard of discounts on passes, but not through runD. The discounts we see at the other races was an effort to fill those races and hard to cancel once issued.
I would love to look at the books to see how well the free Monday worked. I think it probably was a huge money loser for Disney on multiple fronts.
1- most folks I know did not extend to take advantage of the offer so no additional revenue.
2- most folks who were not AP's simply did not purchase a pass for Monday - los of revenue
3- every half runner I spoke with was PO'd so there is presumably a cost increase associated with manning the feedback channel.