Not sure how you avoid such an important number in a tech showcase. It will come out regardless.
It will come out once people have analyzed the specs sure, sure. But they can always dodge stating the TFlops number, by putting the power in terms of the currently existing consoles. 2.3x the power of a ps4, 3.2x the power of an xbox one. etc.
Makes it easier for the journalists, media and general public to latch on. "More than 2 times the power of a ps4" "more than 3 times the power of an xbox one" makes more sense for the non-enthusiast reader than "x teraflops" does.
I think you have to consider Xbox One S is $400 so why would Sony release a console ~3x the power at the same price?
1) It's the 2TB version of the Xbox One S that is $399. The base model is $299.
2) I think you should also consider that Sony launched their more powerful console for $100 cheaper at the start of this gen. If they wanted to, they could've easily priced it the same as the xbox one and justified the console being that price due to the extra power even though it didn't include the camera, but didn't.
3) One of the reasons this console is even coming out is because the cost of doing this versus a slim version of the base ps4 is actually not coming out to that much difference, and it's going to help keep the momentum of ps4 sales going.