Regional intergovernmental organizations are attractive to many countries because they

Regional Inter-governmental organizations are attractive to many countries because they "promote a region's common values and interests".

Explanation:

Regional Inter-governmental organizations provides technical assistance and policy advice to support sustainable economic and social growth in its regional member states. Such organizations also integrate international membership and include geopolitical forces that exceed operationally a single nation state.

Many regional inter-governmental organizations tend to work side by side with well-established multilateral organizations, such as the United Nations. While a global organization is in many cases simply referred to as an international organization.

The very common examples of Regional Inter-governmental organizations are as follows: African Union, South Asian Association for Regional Cooperation, Arab League, European Union, Union of South American Nations, Caribbean Community etc.