It very rarely rains enough to have them on constant, but even if it does it is only an extra click, no big deal and certainly not worth paying silly money to be lazy and not have to do it.
It's nothing to do with lazyness, driving a Motorway journey for example in variable weather is so much better with rain sensing wipers - you just turn it on and forget about it. No need to keep faffing about the wipers every time you pass a truck or something.
Besides, £200? They are standard fit on most cars surely
