Car hire is unfortunately always a pain in the backside! whilst it is cheaper to have your own insurance you have to be very careful about recording the condition of your hired car including photos otherwise they will get you for the smallest of scratches!!- when collecting the car you are usually in a rush and the light often dim!
Not taking the hirers insurance can restrict benefits like breakdown assist and return with full tank of fuel, the former the more important
I suppose car hire firms have to make a profit and the need for portals to offer the lowest basic price has brought about the current situation which is basically 'aggro car hire' unless you take their insurance
I am usually hiring out of season and have to admit that I have had enough of the aggro, given in and take the full insurance and have a peaceful car hire: how it used to be in the old days- had a 7 seater in March for 3 weeks at cost of £250 mainly insurance!!