Yeah. I'm of the school of though that thinks nearly all web content should be preserved at it's original url. Wayback is a godsend but it should be a last resort.

My guess would be one of the main causes of this is "can't be arsed to migrate Wordpress." I've done that and it's surprisingly straightforward (with a plugin), but I guess FTPing a folder involves less mental steps (so has a lower "activation energy".)