guahh my dog is so cute
I think it is that everything is already laid out in the exact style people expect from a Pokemon game. Every little quirk they remember from that game as a kid from the running animations to the sound is ready and available to them. The Pokemon Essentials kit only provides a decent simulation however, and due to it being based on the RMXP engine it too has it's limits, and it ends at perfecting the Pokemon style.
However, if someone was to program an engine with the aim to seamlessly emulate that style while creating the tools necessary to create a game like Rom hacking has (XSE, Advance Map, and the large amount of tools created), it would be beneficial to the GameDev section, but that is a whole another problem unto itself.