I wouldn't go so far as say conditions are extremely dangerous. People with the right equipment and clothing, and a reasonable knowledge of how to use crampons and ice axe, AND an intelligent head on their shoulders SHOULD be ok.
The death was a freak accident on the Mountaineers Route -- nobody saw it, and dozens of people make it up and down the same route every week. The rescue from the summit hut was caused by a seriously bad case of Summit Fever -- NO sense of having a turnaround time. Read here. (They were warned by other hikers, but maybe not strongly enough.) The avalanche was on the North Fork Lone Pine Creek (the Mountaineers Route approach). Over the years, the only reports of avalanches I've seen on the Main Trail side have been after heavy storms in mid to late winter.
As for clothing, unless you are heading into stormy weather (and you would be foolish not to cancel in that case), layers and wind-proof clothing would be in order. I don't think full-on ski gear (at least the insulated pants) is necessary. Skiing, you are sitting on a lift in foul weather. On Whitney, you are expending a lot more energy, and so ski pants would be too hot (unless you were waiting for a rescue in the summit hut. )
Here's the NOAA page for Whitney summit weather. (Weather page link is always above on the left.) Watch it closely leading up to your hike.
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