i think you also need to factor in the history of the s1 and s2.
the original s1 - of which around 25 were built - were fundamentally underpowered and not really fit for purpose. they were eventually grounded i think for having unairworthy engines and could not be turned into s2s.
the s2 was what the buc should have been, but some years later, with engines 40% more powerful (err, thats alot).
modern development techniques go to great lengths to try and avoid making 25 examples of a non-fit for purpose product - it would just be unaffordable and unacceptable today to do so, but back then was a different time.
don't misunderstand me, the buc was a great platform from many perspectives, and the sometimes asked "what if - with tornado avionics" question is a good one, but be careful with the rose tinted hindsight specs!