I'm wondering if BoT can be modded so that, like most globals, it only takes effect within the caster's dominion. That way it would still be useful for Ermor, CW, and Desert Tombs, but not as horrifying.
The alternative for me, especially for SP games, is to completely remove it, or avoid nations with death magic. The spell is bad enough, but when Vanheim or the like casts it, it's totally ridiculous.
Edit : Just as bad for MP, what with having to constantly check all your mages for disease and all - the aggravation factor makes people want to quit the game right then and there.