The Scient situation particularly makes sense. They grew at a simply unbelievable rate (almost 2,000 employees in 3 years, it took Razorfish over 5 years to get to that point). Any of the major 6 or 7 firms probably had enough money to grow at that rate, but having the money doesn’t make it easy. It’s hard to make that kind of growth sustainable.
Even without the layoffs, I question how long that could’ve gone on. IMHO, growth at that rate makes it impossible for a company to have a coherent culture, and without a strong cultural affiliation with the company, the employer is just another commodity from the employee’s point of view.