The design intend of slime cat was very obvious. Blizzard knows their playerbase super well and FOMO would push people who do not care about raiding one bit to doing normal raids.
This would also mark their so called “experimental season” as successful which means this kind of design would continue in the future as well.
If any of the LFR players actually cared about their play style, they would boycot the raids and forget about the slime cat, otherwise Blizzard will pull this same trick again and again in the future.