I think an option to disable it would be good, but I would definitely not use it. For ults like ezreal and ashe I use it all the time to aim at people across the map or in ezreal's case to farm. I always sat in my games of LoL and watched an ezreal completely miss his ult, sometimes in the complete opposite direction thinking they were completely clueless only to have it happen to me. The enemy was near where my minimap was and my mouse just so happened to touch the minimap pointing the ult in a completely different direction. That doesn't really make me want to change the clickability of the minimap for me, but the ability to change your own preference and how you play I think is a good idea in general.