Well funny that you mention this. Because your deck is now B/G you can look at the Guilds of Ravnica and take a close look at the Golgari Swarm. a Lot of their creatures are of the B/G variety and creatures such as
stonefare crocodile (for the life link),
trestle troll (for the
regenerate),
Lotleth troll (for cheaper
regenerate), and even
groundskeeper (to get lands back that you may mill to the graveyard). These are some options that you can implement into your deck while still keeping the pressure on your opponent. And yes a creature focused deck is of course a viable strategy. Think of it like this, your creatures are the front line to your
castle. If you have no defense then your opponent is just going to stroll right in. You can throw your
fire balls at them (spells) but if they are resilient then they'll get by. It's important to have strong forces up front because they can be used for both offense and as a deterrent.