Standards might make things "easier" in that everything is generic, but I think there are other considerations regarding design (both function and aesthetics) that require customization of thumbnails. I base this only on viewing many artist's websites and designing sites for my own paintings, where using thumbnails is often or always the main component of the site. Maybe because it's artists' sites, the more unique and creative the better. But I see that adult web design is getting much, much better, some incredibly inventive things happening by really creative designers in this genre, too.