No it's not brain dead neither is it worse. You know what made Lucky star fail? It tried to be cute and didn't quite pull it off. It tried to appeal to Otaku culture and it was overly blatant. It tried to viral market a shit ton of works but it also failed because it was obtrusive.
If you think Strawberry marshmallow was boring then it's because you watched it with some expectation of slap stick humor, great action sequence and other more exciting things than just a bunch of little girl being little girls. I don't know what you expected but it's not our fault neither is it the fault of the series. In it's own respect it fulfilled it's objective, precisely cute little girls doing things that cute little girls enjoy while maintaining a relax atmosphere.