Having done basically this same project before (but just adding amber LED indicators, no MCU) I’m a bit confused over the use of the sensors vs a relay on the e

Having done basically this same project before (but just adding amber LED indicators, no MCU) I’m a bit confused over the use of the sensors vs a relay on the existing indicator wiring. Was it to save from splicing into the factory wiring? If so, as an alternate method, on mine I got some of the same connectors used on the factory indicator wiring to add an in-line split off to a relay that triggered my new indicators which were then powered directly off the battery. This made the entire system very simple and reversible. I wanted to do mine animated like my car but I wasn’t sure how well MCUs hold up to the pretty extreme vibrations bike electronics get submitted to. Plus I’m lazy.