I've always defended the play off system, as everyone knows the rules at the start of the season.
But I agree, if either fails to go up this season it'll seem unfair as they are both miles and miles ahead of the rest. The playoffs will be an ordeal for the fans, whichever it is, as the opponents have absolutely nothing to lose and the pressure on them will be immense and inevitably lead to mistakes.
It's probably worth betting against them in the playoffs as I'd say a slip up in these games is more likely than a slip up in the league and the odds will be healthy.