People may prefer capital over humans purely for selfish reasons. Money coming in your region, assuming you have some degree of control over it, usually help the local economy (growth of jobs, wages, assets) unless its already inflated one like SFBA. Humans on the other hand tend to be a mixed bag. Highly talented migrants (whatever definition of talent suits you) should be a boon to your region but same cannot be said about untrained undeveloped masses.

For a politician, it would make sense to advocate for easy capital inflows, somewhat controlled capital outflows and highly selective immigration process.