It's more of demand and practicability over time. Like what the gurus like to refer to "Last time no AF, also can do sports, no 8fps also can do sports".
The f2.8s have their beauty like the older AI-S. It's not necessary better, but it gets the job done. Like your example. the 20-35 f/2.8 was a gem in the older days, to compare with the 18-xx/xxx glasses these days, it's definitely a hands down comparison. The 17-35 was created for that extra 3mm and to replace the 20-35. Doesn't mean the 20-35 sucks, but demands do grow.
Like what you felt now, am sure the 14mm is tempting as opposed to the 20mm. Similarly, that's what enticing me on it when I already have 17-35.
Also earlier, I did mention, the 3 f/2.8s are a glass (class) on their own, they do not necessarily lose out to primes, but they do not necessarily win every prime. Same as for the 20-35. Primes do not generally win because they are prime.
Take it with a pinch of salt.
i think during film days, sports photographers use bulk back and motor drive and shoot whole roll of 250 frames in one shot?? my fren told me so, too bad i am too poor in the past to try film .. but i think digital did make it easier for more to try photography, but not neccessarily make us better photographers.. ;p
35mm film - Camerapedia
The MF-4 250 Bulk Film Back - Index Page