The surprising thing about this announcement is that its a private mission. SpaceX has long resisted private tourism, to pursue CRS and Commercial Crew missions. I'm sure several billionaires would have written a large check, long ago, to go into orbit.
Have they really resisted it? SpaceX haven't had, and still don't have, a spacecraft capable of carrying people into orbit, so it's not like they've left money on the table. Delivering satellites and cargo was a good way to fund and prove the rocket themselves, without which any tourism is obviously a non-starter. And working with NASA on the Commercial Crew programme provides access to NASA expertise and facilities that SpaceX would otherwise have to develop from scratch. I suspect tourism was always part of the long-term plan.
If I had to guess why they decided to start with this mission in particular, I think it is probably because it provides a better PR opportunity than simple orbital tourism. SpaceX are clearly very image conscious, and beginning by taxiing billionaires into orbit perhaps sends the wrong signal. It's not doing anything that Russia hasn't already done, and undercuts the idealistic image they put across.
On the other hand, sending people beyond LEO for the first time in over forty years is clearly a major accomplishment. And having them be private citizens, even very rich ones, sends a very strong message that private spaceflight has come of age.
Yes, SpaceX resisted earlier tourism opportunities for a few reasons. One reason was they didn't have the corporate resources to do tourism flights, and do the R&D for CCDev & Commercial Crew Program (CCP), so they focused on Commercial Crew.
Another reason is that NASA doesn't want tourist flights to the ISS, and no private destinations were close to ready. Lets say CCP funding was delayed, and a private team offered $400m for tourist flights, they'd have to develop two different Dragon capsule specifications. One for ISS, and one for private tourism. Similar, but with non-identical requirements. With the CCP further along, the different specifications may no longer be an issue.
Another reason is SpaceX doesn't have a training program for space tourists, and they'd require a training program. The Russians require 3-6mo of training for a space tourist on the Soyuz.
That said, there are reasons SpaceX went for this plan now, and not before.
Indeed, the last time people went beyond LEO was Apollo 17 in 1972. Having the capability to do so is a big step towards re-attaining the Apollo level of humans in space.
The surprising thing about this announcement is that its a private mission. SpaceX has long resisted private tourism, to pursue CRS and Commercial Crew missions. I'm sure several billionaires would have written a large check, long ago, to go into orbit.