The BBA is a feel good action, that's all. Common sense says the budget should be balanced.
We can deal with the spending level issue later.
We need to address spending now.
Yes, and the BBA isn't going to make that happen. The ratification process can take a long time -- it's typically limited to 7 years when the amendment is proposed.
I'd rather get the amendment in the pipeline, and address the spending issue at the ballot box. Putting a spending limitation in the amendment will make it more difficult to achieve the 3/4th's of states for ratification.
Making it a separate amendment is another way to address the spending issue. You might even find that some states decide to ratify it, and not the BBA -- but both amendments achieve the required 38 states from different sets.