The only reason why the cut-off was only 1:39 was because the BAA added an additional 1,500 entrants. The cut-off likely would have been 2min+. I'd say they increase it for the 125th running and we'll see a similar cut-off for 2021. In another year or two the BAA will have to tighten the standards another 5 minutes.
No the standards are not fair across gender or age groups, too bad. Life it's fair. Deal with it.