I believe this is what happened to Dr Who. When it started it was for science and history nerds, science sounding gobble-de-gook, cos play outfits, very low production values (the infamous duct tape boots). All just good fun.
When it was rebooted the focus had shifted. The Doctor as the cool guy, a Jesus figure, became more and more pronounced. They started to make fun of nerds on a regular bases. Amazing writing and production values, but at some point during the Tennant era I stopped watching in disgust.
The original Doctor Who was an educational show mostly aimed at school aged children that used a sci-fi gimmick to teach history lessons (much of which are a bit outdated now). They would alternate storylines between future and past settings through most of William Hartnell's run.
Towards the end of classic Who it was already much more like modern Who than those first seasons.