Corporations can't pony up the money for exploration if we don't first have the technology to do it. We should be exploring the universe for the sake of science, not just profit. Increasing our understanding of the universe around us is beneficial to all of man kind.
With all due respect, corporations - and every other form of business - will pony up the money and will develop the technology - without a smidge of "help" from Uncle Sugar - if/when there's a realistic prospect of a positive return on investment. And there isn't any "we should" way of getting into, exploring, and exploiting, space - any legitimate use, whether private or public, that an individual or a business wishes to make of space is just as much a "we should" as is anything else. Knowledge solely for the sake of knowledge is sterile; knowledge has no value until something can be done with it.