He doesn't really have a way to quickly apply BC stacks to multiple targets. Heck, he doesn't apply it to single targets all that quickly either.
As for BT, he already has a ridiculous amount of lifesteal with his passive (an even more with lifesteal quints). Spending that much money on AD isn't a good idea either since his primary damage source is Q stacks. The gold is better spent on resistances, health, and CDR.