Different strokes for different folks.
The BB is especially for base malt, where 25kg is not actually that much when you chew through 4-5kg per normal-sized batch.
If the difference of $10-20 per bag is not an issue, then BBs are probably not your thing. For me, every penny counts so BBs are great when i'm ready to stock up. Also, i don't have a problem w the BB schedules - i'd prefer to do a single massive purchase every now and then and have very grain i'm likely to need at home already, rather than go to the LHBS every time i want to brew something to get that extra 500g of X.
The 5-way splits for specialty malts is great for most spec's to access a similar saving.
For better or worse, BBs tend to result in going home with a ridiculous amount of grain, with which you can then fill your treasure room and gloat like a fat dragon.
Also, having all this grain on hand can encourage you to have a crack at different styles, given you've got the stuff sitting around anyway...
BB FTW!!