Dashed bike lanes: Better than nothing, or total trash?

There's an increasingly popular slogan and hashtag among bike advocates, "Paint is not protection." It's basically a factually true statement: Bikeways that consist of road markings, with no three-dimensional barrier or grade separation between people driving and folks on bikes, do not physically prevent the former from striking the latter.

Here in Chicago, the catchphrase is regularly used by advocates ranging from fairly left-leaning folks like the person who runs the Milwaukee Avenue Bike Lane Twitter account, to the relatively non-radical, Chicago Department of Transportation-friendly Active Transportation Alliance. The implication is that when city officials install paint- or thermoplastic-only bikeways, they're short-changing bike riders, generally due to the officials lacking the guts to take more space away from motorists.

Or do they represent a depressing surrender to car culture, when city officials should be doing whatever it takes to provide physically protected or grade-separated bikeways on retail streets? Judging from the responses to the above tweet today, many local bike advocates take the latter position.