You cannot discuss 1.14.4 texture packs without mentioning . While not a texture pack itself, most high-quality packs for this version rely on OptiFine features:
It sounds like you are looking for the backstory on why are such a significant, and sometimes confusing, topic in the community.
Because 1.14.4 stabilized the code after the buggy launch of 1.14 and 1.14.1/2/3, this became the golden age for texture pack creators.