I heard somewhere that in Holland every bicycle + lock weighs 5kg. If you have a cheap 5kg bike no one wants it and you don't have to lock it. If you have an expensive 1.5kg bike you need a lock that weighs 3.5kg to protect it.
Most light and simple(no suspension) road bicycles weight usually 10 kilos, most mountain bikes do weight 15-20 kgs.
In Holland, most bicycles you see on the street are simple and cheap.
And a 1.5kg bike? What kind of bikes are you looking at?
In general, since we are so flat a country, bike weight doesn't matter much. We'd rather have extra fancy stuff on a bike than have a lighter bike.