I think it's better the way it is now because it helps generate more volume for CUB and hence more trading fees.
If CUB-BNB is the major pool, then CUB's price will move with BNB's price. It's easy to arbitrage a low liquidity CUB-BUSD pool.
However, when CUB-BUSD is the major pool, BNB's volatility leads to lots of arbitrage opportunities which require more volume.
I might be completely wrong on that, and have no evidence. Just seems intuitive, although my intuition was wrong many times before with Defi stuff.