The reasoning behind no concessions is that 20 years ago the spilt of supportes was 70% to 30 % concessions , now it is 30% to 70%. the other way. I think you will find more clubs doing this, with the match ticket being a ground entry tickets so it costs the same to sit or stand, your choice.
The whole matter of concessions at sporting events is a throwback to past years, do concessions apply to food shopping, restaurants , concerts etc, it applies to transport but only at state pension age in West Yorkshire . Why should clubs, who are business's, give away cheap tickets to a percentage of the population who have more disposable income than a family in there 40,s.
Some may say it's for being a loyal fan over the years, but I know plenty of fans who have 40 years supporting, at what point do you become a loyal fan !!