Running a budget surplus or reducing a budget deficit and reducing the national debt implies that government spending is coming down and/or taxation is rising, which is contractionary fiscal policy, also known as austerity policies
Cutting government spending on education, healthcare, infrastructure, public sector wages and welfare can harm living standards and quality of services
Increasing direct taxation like income tax and corporation tax can harm the long-run productive potential of the economy and constrain long-term growth rates and prosperity
Higher direct taxation can create incentive distortions like lower incentive to work, be entrepreneurial, and greater incentive for tax evasion and avoidance