I'm merely recommending a practical approach to reality. Weigh the circumstances. Maybe that 4-hour flight is worth $199 to buy up FC. Maybe that 2-hour flight is not. Take your chances on the latter, not the former.
I suspect many flyers are already doing what I do, which is pay up at booking (either with $$ or an instrument) on those flights where I will be really unhappy if stuck in back. This, to me, feels very similar to what we used to in the "good old days" before upgrades were complimentary.