The orientation of the original fan was an assembly error. PSU fans should be mounted as intakes, with the fan blowing air over its struts into the PSU and out of the rear exhaust grill. As you note, with the current configuration the fan is attempting to stream warmer air into the case which is hardly desirable.
I'm not so sure as on the inside of the part of the fan nearest the rear/power switch it has a piece of plastic blocking it, which makes sense if it's drawing air in the rear vents to prevent it going straight out the fan, thus forcing it to flow over the far part of the board before exhausting out the other half of the fan but not if it's meant to be an intake, in which case I'd expect the plastic to be on the outside of the fan to force air only to be drawn in by the furthest part of the fan. Having the plastic where it is if it was meant to be an intake fan would seem strange, as then it would be drawing air in that half of the fan only for it to hit the plastic at the bottom.
As I said, with many cases (including mine) the fan is blowing directly out of the case (the bottom in my case but some will be the top) so perhaps they had that in mind when designing it and didn't take into consideration the low-end cases where the fan would be blowing onto the CPU.