I ride motorcycles in cross-Europe trips for fun but prefer the GPS. My GPS will look for small twisty mountain roads with lots of elevation changes and lots of corners. Roads that are only on highly detailed local maps, and I don't want to carry 30 maps on a month long road trip. Road signage is simply not a thing on these roads as they are only used by locals. I can disable highways, B-roads, toll, ferries and on my roadbikes I will disable gravel sections. It will tell me how many kilometers till the next gas-stations along the trip and warn me about speed traps. Not that I speed on purpose, but sometimes you are a couple of kms above the limit.
Especially on sections where I have to change direction every 300 to 500 meters I don't want to deal with reading a map. Voice navigation in my headset and an occasional quick glance at the screen is much safer than fiddling with a paper map.