I love it when people still have faith in either party cleaning up the tax code (aka reducing the size of government). Ain't happening.
“Cleaning up the tax code” and “reducing the size of government" aren't really the same thing; the former could very easily serve the opposite purpose of the latter.
Or, not; alternatively, it would allow the IRS to be more responsive in its supportive activities and more effective in its enforcement activities.
Cutting staff is a separate decision from streamlining the rules; the IRS hasn't had staffing expanded to keep workload constant when we weren't simplifying, there is no inherent reason it would ha r to cut staff and keep workload constant if we were simplifying.