I suspect the lack of interest is less to do with Sunrise and more to do general lack of interest (on this forum) toward anime that doesn't have an existing manga or game following or immediately leaps out as being a hit (or have lolis in it).
That can all change of-course once the subs out. Dare I say look at The Melancholy of Haruhi Suzumiya, very little if any interest before the first ep then bam, spawns a inescapable gif-making fanbase of biblical proportions. I doubt that'll happen to Bakumatsu but you get my point.
