There were 137 managerial changes at other clubs during his tenure as manager. There's no loyalty from fans or the board towards managers. Remember Jimmy Melia, Steve Gritt, Russell Slade? They were all sacked a few months after achieving memorable things for the Albion.
Many of those changes were enforced and I certainly wouldn't criticise any Manager making the next step up, that's progress and it happens in most environments.
The way Poyet went about it was disingenuous and disrespectful. No problem with him having ambition and moving on but the manner in which he chose to do it means he has no place in my hall of fame
I recognise opinions are divided on this and there's no right or wrong. Perhaps it's a matter of what one draws the the line of professionalism and integrity, but for sure Poyet is pretty unique in the way he went about pursuing his ambitions