Not a BRC expert. Reasons?
Well for starters, he loses his 8 frame mid which is hit confirmable, multi hitting (can break armour on it's own) for an 11 frame high (has good range but apart from that it's balls) and that 8 frame mid is the only decent mid he has at all. His only other mid is b2 which is 24 frame startup so it's pointless for pressure. Loses his 11 frame low starter in b1 for a 14 frame mid, into overhead. If he uses b14 in bartitsu there is a gap, b12 in DM and DB there is no gap. The only way to meterlessly launch your opponent in bartitsu is with 341 or 413u4, which are both Bo's universal strings and both are punishable on block. (although 341 can be kinda tight, 413u4 gives you a year to punish) There is no way to meterlessly launch your opponent in bartitisu. You have to hitconfirm into df3, which needs to be meterburned for the launch, hitconfirm in db2, which has to be meterburned to launch or even worse hit confirm your grounded string like 1212 into ex db4 because the regular one doesn't combo on the ground.
Moving on from that drunken master has the rolls out of his meditate stance which has INVINCIBILITY so that is huge for him being able to get in. It also makes virtually any unsafe string he does safe because he can cancel into meditate and roll away from his opponent afterwards. Bartitsu is unsafe on every single one of his specials. df3 is unsafe, db2 is unsafe unless you're at max range (also not armoured in bartitsu like it is in DM and DB), db3 is unsafe (another tight punish but still), bf4 is unsafe and also doesn't have an armoured meterburn version like DB and DM. Generally speaking bartitsu's damage sucks ass especially compared to drunken master where you can easily hit mid forties meterlessly in the corner and high thirties mid screen. Bartitisu can struggle to get mid thirties for a bar midscreen.
Worse mobility, worse damage, more meter dependent, no good mids, unsafe. Literally the only thing going for bartitsu is his range and his mixup potential with db3 and df3 combined with all his strings that hit low/overhead. Drunken master is not bad, it just takes good management of the drink which is very difficult (difficult to use does not mean bad). All that has to be done is a slight alteration to the drink mechanic (time each drink lasts, drink only goes away on hit or something) and the variation is 100% ok.