Slim,
Whilst I agree with what you write above, it's Ryanair which, as you know, lists both Reus and Girona under "B"!
I have flown Ryanair to both, visiting Tarragona and Girona (both interesting cities) and not Barcelona, so I suppose that, too, provides evidence for what you say.
I'd love to see Ryanair serve El Prat because when I travel to Barcelona this is the airport I wish to use.