If it's worry about lightning, a lot of it depends on just how effective the ground system the antenna switches to is and how well the rest of the station is protected. If the ground to which the antenna is switched is poor (which means like most), I wouldn't consider it much improvement to switch to ground. At any rate, a double make, double break switch is best. (Physical conductor that completes the antenna center conductor connection moves to connect to ground while leaving a conductive portion to intercept any arc attempting to cross the gap to take it to ground.) But they still depend on a good ground when you consider how much air it crossed before finding the antenna. Although I don't worry much about lightning, I still put in substantial protection, all passive, because (1) it doesn't depend on me realizing that I should disconnect and (2) it's likely effective with near strikes and strikes on the electric service, as well as on the antenna.
But yes, I'd agree that those common DowKey switches are really just relays with very small gaps when open. Hardly worth the effort when you have to do passive protection at the station end (as well as a good ground for any antenna mast or tower, which is where a lot of the energy can be dissipated). Without an adequate lightning ground, about all that would do the job would be a monkey trained to disconnect the feedline from the station and coil it up at the tower base. I've really come to believe that, without the good ground system, there's just no antenna switch that offers any real lightning protection, for all that the makers seem to harp on that as a benefit, and, if the right kind of passive lightning protection is in place, you don't need the switch for that purpose.