I think part of the image problem that "modern art" has, stems from the fact that it doesn't translate weel into other media. People read a description of the lights going on and off, or see a clip on TV, and feel that they are then qualified to judge the work on that basis. You might as well judge the taste of a meal from a photo.
Most people don't have much interest in art anyway - they go "what a load of rubbish" at a newspaper report on the Turner Prize once a year and completely ignore it the rest of the time. At least something like Martin Creed's room with the lights going on and off is engaging people's interest, even if it's just a knee-jerk reaction of "I could do that!". Yes, you could - but you didn't.