The IRS is critical to stopping fraud and making sure everyone plays by the rules. Currently, we have folks not respecting the rules and getting more economic influence than they deserve. The current climate is an effective tax on honesty.
As long as budget increases to the IRS increase revenue to the government, they should keep growing.
If you take issue with individual taxes that you believe don't belong in our tax code, identify one and repeal it.
Why? The government is not a business. They should not be interested in 'raising revenue'. They should be interested in helping their constituents grow rich; not taking their wealth.
This then makes me think that tax law may already account for "under collection", which might cause it to target "over collection". Increased IRS effectiveness can close this gap.
It does however have to deal with malicious actors who ham-handedly try to game the system at everyone else's expense while patting themselves on the back for being clever. Man, if we could just fix this one thing, think of all the general operating costs that could be cut everywhere.