The ANT-25 had to land & refuel to fly back, so even as a bomber it would be 1 way mission if there were no airfields nearby for that.
So it wasn't just that flight that inspired to continue with the B-17.
Are you kidding... we are America... everything we do and have is the best, yet these dumb half asian Russians flew a plane direct from their country to ours... an actual flight distance of 11,500km and still had 1.5 tons of fuel left on board when it landed.
It was a single engined aircraft and no where near their biggest.
It was slow and an easy target for defences, but it was a distance record aircraft not a prototype strategic bomber.
It scared the shit out of them that the Soviets could have such aircraft technology and potential and they realised they needed to catch up.
It was very much like Sputnik getting an American to the moon...
Also to be fair any Tu-95 flying today has new wings... in the 70s and 80s they further upgraded the wing and fuselage design to improve performance... the first beneficiary was the Tu-142 maritime patrol model but all the in service Tu-95s were pretty much made after the design change and included the improvements.
Western experts consistently underestimated the performance of the Bear throughout its operational life because they assumed a much higher rpm rate for the blades, which would have made them super noisy and rather less efficient.
The blades are actually coarser in terms of pitch angle and run at something like 750rpm which prevents supersonic blade tips, which would dramatically reduce thrust performance...
But western experts have always just seen it as a WWII B-29 rip off that didn't warrant being worried about.