F-16XL

I realise the F-16XL was a NASA demonstrator aircraft, but how come it never became a operational variant? The wing area added gave the F-16XL a staggering 82% increase in fuel, stores for up to 28 bombs and the combat radius was also greater, I wonder what the down sides must have been? The F-15E must have been chosen perhaps?

ANNNND If 2 F-16XLs were only made (SHIP 1&2), how come I have found so many different images of F-16XLs with a wide variety of paint schemes? Were they re-painted many times or were more made? I have seen the yellow & black to a low visibility grey USAF scheme to the traditional white, blue & red NASA colors, I know they recently have flown a F-16XL once again to test a contract to study the cost of upgrading and returning Ship #1, the single-seat F-16XL, to flying condition to help with research into sonic boom propagation and mitigation…