The one thing James has never had a decent handle on, is social media. Say what you will about Mike, but when he was in charge of that aspect of the channel, I would say that the series was overall in it's prime, he knew enough of how to work social media to keep AVGN out in the zeitgeist (and you can't convince me that he didn't know that Inspector Gadget thing was so bad that it would be genuinely hilarious, but I digress). Once he left and those Screenwave guys took over, what little soul the series still had, really seemed to be stripped away. It's not like they're solely responsible for my now current indifference for AVGN, as that godawful movie was done well before they came along; but still we're now in an era where the Nerd just feels like a business and no longer like a passion project, probably because that's exactly what it is now.
So in that regard, it makes sense that as a business they'll keep updating the youtube thumbnails as time moves on, and the kinds imagery that leads to blind clicks on videos continues to change. I'm sure it will happen again and again as the years continue to move on.