If people start dying left and right, funding for the programs will be cut, and it'll be many many years before things can recover and people will try again. I don't view it within human nature to spend all your money on people bent on crazy suicide missions. (Not that I think it is one, but with enough accidents, people will get that impression). If you do this wrong, it's more likely to set us behind on a goal of colonizing Mars than to help us achieve it. With that said, I wouldn't be surprised if people die in an attempt to colonize Mars. Even if reglar safe passage becomes possible, people still die in car crashes today which are considered regular safe passage. And yeah, I do expect many people to have that explorer attitude. Certainly if they kill themselves with their own private money (and not too often), people won't care too much.
As for the transit, I've heard most estimates at over 6 months (but not seriously over). Now, for the gravity thing to be useful, a significant portion of that time would have to be spent under those conditions. I don't see how a 1km long teather is practical, useful, or even safe. Unless you're putting some stress on your bones, by say standing against such a force, what's the point? For a teather to be useful, it'd have to be made so they were standing in relation to teather with their feet supporting them. Certainly possible, if a little awkward. Now, what would they be doing meanwhile? Just standing there? 1km out on a teather? With no worries of anything going wrong? How long would it take to get back into a ship in an emergency? And don't go telling me the ship is gonna be 1km in radius. Besides, people need to be doing something useful, not just swinging around in circles all day. You need to subject them to a force as they go about their normal daily operations. Or at the very least, provide enough daily exercise to keep them from becomming gelatenous blobs by the time they reach Mars. Yes, I know rotation can give the effect of artifical gravity, but for it to be practical, it'd have to be only a fraction of what we're used to.