I couldn't agree more, but if you've ever seen the "actual" JSF that Boeing was "going" to produce with a similar tail structure as the F-35.....it actually didn't look all that bad, just sucks their technology demonstrators were hideous.
You're skipping over a major issue as to why they lost. The tech demostrators were supposed to be pretty close to what would be produced hence the willingness of govt to fund them for the assessment of the two contenders. To not make your demonstrator indicative of your final design is foolhardy. hardware on the ramp counts much more than a Powerpoint promise.
Boeing discovered their initial design needed horizontal stabs in the process, but did not include them in their demonstrator so the risk assessment went up.
Regardless, the design in your photo still had that guppy belly. It's just masked by the angle. In the words of a driving companion last week pulling into Pax and him seeing the demonstrator for first time. "What were they thinking?"