I agree that 40% is an insane tax rate, but it's only on the value that exceeds the government's health care allotment. Maybe that's a substantial hit and maybe it isn't, I don't have enough information to judge. If 26% of Americans are hit but the average hit is a couple hundred bucks or less, it's not exactly a catastrophe. If 26% of Americans are hit but the average hit is a couple grand, then we'll see this delayed yet again and probably reduced and/or phased in so that people don't take the hit (financial or a drop in coverage) all in one year. Gotta remember too that the ACA is merely one step in switching to government-provided health care, which people aren't going to want if their health care is better and cheaper.
Ideologically I agree with Glenn that people should pay for their own health care. Practically speaking health care is too expensive for a significant number of Americans to afford. Having those people die because they can't afford expensive care and diagnostics is neither moral nor societally smart. Raising the cost for those who can afford it is the only practical way to bring an acceptable level of care to those who can't afford it. I love me some free market individualism, but it's not the best choice for every single situation.