Totally agree! For all non-english bloggers the fact that a theme is i18n ready is definitively a needed feature! At least the premium themes need to be i18n, but very few are!
Even all the free themes listed at wordpress.org sholud be i18n ready, as WordPress is...
I agree, and @Jé: the point is tha aven for security upgrades they put new features in the box, or change some admin panel etc... so you have to upgrade for the security concern but you ends in haveng an "empowered" Wp even if you don't need it ;-)