To prove we have the will and the capacity to do it.
The capacity is there for any nation with the technology and money that the US had. Back in the 1960s.
I'd rather ESA had the will not to.
The ESA should be at the forefront of all space technology from probes, satellites and to manned space vehicles.
There's also big money to be made from developing the Skylon and it will be good publicity for the ESA.
Skylon can ferry cargo into space, it doesn't need to ferry people. Why should ESA be reduced to stunts for national pride?