On the other hand, when was he ever good? Sure he had one or two races in his career that were good, but then again so did many forgotten drivers. He had two top 5 finishes in entire season, despite being given advantage in form of fan boost throughout entireity of the season. Multiple retirements, many of them through crashes, penalties and other mistakes - it just doesn't add up to me to call Vandoorne good.
Having said that, it is a good idea from PR perspective to keep him I suppose, for some reason he has huge fanbase which results in fanboost every race, so maybe keeping him for marketing reasons makes sense.
Oh yeah, because that gave him a big advantage.
Vandoorne didn't even use it when he was battling for positions because fanboost is pretty useless. Fanboost accounts for 0.00001% of overtakes in FE.