I was thinking about it yesterday and wondered if they should state the fastest lap point can only be claimed up until e.g. 5 laps (or whatever number) before the end of the race. That way you are still rewarded for a fast lap but you have to decide if you want to risk giving up the 25s or whatever to come and put with there still being a few laps to go, because even if you have a 30s gap to the next car, there's a chance you might lose the place, plus potentially backmarkers to factor in as well.They need to do something to do these silly fastest lap runs if they keep the point.
At the moment, the fastest lap point often seems to just be pot luck based on what track position is like heading into the final lap, e.g. you are out of the points so you just pit for fresh soft tyres, or you have a big enough gap to the next car that you can pit without losing points. Although obviously not every car/driver will be competitive enough to challenge for it anyway.