Why Fallout Lost Its Original Artstyle

It's clear to most fans and enjoyers of the Fallout series that the newer artstyle has taken a drastic change from the older games. Fallout's artstyle used to build a bleak atmosphere but now it builds an atmosphere focused on retro-futurism. What reasons caused Bethesda to make these changes to the franchises' artstyle? Credits: https://youtu.be/h24El8Ofim4?si=z_Fm2LAWmcbCWnYi https://youtu.be/AywyIgH0IzU?si=7uJo0pmOJHf6pU4g https://youtu.be/L8cERrMSXjI?si=vZGnKZEXYafMeX_q https://youtu.be/WQeOiYjj8ig?si=MCTFi525HGDQtZ1R