Sounds like a good idea. Nations (and Unions) need big bold aims, to energise scientific research, the economy and people’s imagination.
I am not particularly interested in a mission to Mars as such, but the fallout from such an undertaking would be enormous. Public funding and control is indispensable, simply because private enterprise goes after the “low hanging fruit”: projects which can bring a relatively quick return on investment, while they couldn’t afford to finance a 10-15 year project, involving a lot of fundamental research. Research and development jobs for thousands of European scientists and engineers, cooperating with colleagues from around the world – that would be a very positive development.
I followed the Apollo missions and man walking on the moon live on TV – I wouldn’t mind seeing it again, some day.