My love for the Eternal formats of Magic is undying, even during the dark periods when they're at their worst. Even when there's something truly broken going on, the financial investment required, deep card pool, and dedicated archetype players that show up to all the events produce a tolerable level of diversity. Few players can ditch their beloved Bant Infect deck to craft Grinding Breach, and even if they were able to, most don't want to.
You become attached to the cards that you've cast since childhood, as well as financially locked to a few different decks that share a similar card pool. This is what has made Modern and Legacy popular formats since their inception. Even with the resiliency of these older formats, many players want format health restored so they can achieve maximum satisfaction in their Magic Online (MTGO) League, Friday Night Magic (FNM), or premium event of choice.
There's a weak argument that nothing needs to change and everything is great in Modern and Legacy. Skeptics will point at deck diversity, ignoring the variables I just laid out . . .