Yeah I think until we can teraform and colonize a planet, or at the very least extract resources(water from Mars?), space missions are more PR to justify/garner support for additional public funds for their programs. Don't get me wrong we've needed all the missions to understand what we do now and move on to the next step, and I think it's proven that every dollar put into NASA creates exponentially more value. However politicians like to see votes for their decisions which require tangible and very public displays. Even in the private sector competition among Virgin and Space X for example will definitely spur fast innovation and development, which with public opinion very favorable about space it'll please their shareholders and/or investors much the same way.