It's not like it's some new situation, either. FIA have precedent for introducing stricter deflection tests midseason in order to address what are so blatantly purposefully designed flexy wings, which are 100% against the intentions of the regulations. They just seem to have refused to do so this year for reasons most people can probably guess.
And it's not just about being about against the regulations, it deprives us of more 'mixed setup' racing. Teams can race with less compromise, which allows them to perform at their best in a much higher percentage of situations. Some people wont mind this, but one of the aims of having something like parc ferme is that teams will have different strengths/weaknesses based not just on inherent car properties, but also setup differences, giving us the potential for more interesting racing.