Also worth noting the number of people who interpret the rule exactly as you did LK because all the extra rounds otherwise required before you can do anything useful with grapple do no one any favours
There are also people interpreting it that way because it was was erroneously written and it had nothing at all to do with any extra time it takes.
There are a several reasons I am an advocate for characters not giving extra grapple benefits to their opponents if they fail their check:
First, there aren't really any other game options that give you anything if your opponent fails at something that don't require you to have purchased some sort of ability via Origin, class levels, feats or proficiencies (tricks).
Second, it leads directly to my response in the linked thread where the best tactical course of action for the lesser skilled grappler is to do nothing and Delay his turn away. The alternative is to struggle and make things easier for the guy trying to pin/kill you.
Third, there is a Wrestling Supremacy trick that allows you to Coup de Grace pinned characters. That someone can get held on Initiative count X, pinned on X-1 and then Coup de Graced by someone else on x-2 is pretty lame. Yes, there are other forms of attacks that can bring down targets just as quickly, but just about all of them require at least a critical success along with action dice expenditure to activate said critical and none of them require the cooperation of the guy they are trying to kill.
The last one you don't see as often, but up to 4 opponents can grapple a target the same size. If you get grapple benefits from your opponent's actions, you could theoretically get up to 3, 4 or even 5 grapple benefits per round if you can beat all the people who tried to dog pile you.