Monte may have left because 5e is still too entrenched in numbers

An email from Thomas Reid had been posted on Dragonsfoot about why Monte left WotC. The exact contents are now gone, because he's backpedalling like mad and has asked the various forums where the email had been posted to remove them. Sadly, RPGSite's moderation dropped the ball and went in direct contradiction to their purpose of not censoring things, and deleted the email as well.

I don't have the exact text anymore, but the general gist is that Reid is a friend of Monte's (they both worked for WotC in the past), and one of the reasons Monte left WotC was the company has been insisting that modifiers for every little thing be kept in the game, even if it makes the game more complicated than necessary. Apparently, Monte was disillusioned with the progress on the game because of this, and Reid and others were aware that he was unhappy and likely to leave.

Now maybe Reid was full of crap, but that was the general intent of his email. He didn't know it was going to be made public, so I suspect it may be correct.