I'm not sure if this varies by franchisee or not, but I've heard some formerly loyal Snap-on users say they stopped buying because the warranty got worse, so the element of service (truck showing up and swapping your broken tool for a new one without issue) that they expected was taken away and the price no longer made sense just for the tools alone.
I'll echo what others have said. Cheaper alternatives like the HF Icon line, Tekton, Gearwrench, Sunex, etc have taken a huge bite out of Snap-on and MAC for offering competitive enough alternatives for half the price. And that's just for hand tools. With the toolbox market, is anybody paying $10,000+ for a Macsimizer anymore? There are more large toolbox options than ever before, and many of them are very nice and for a fraction of the price of a tool truck box. I can't imagine Snap-on/MAC/Matco sell nearly as many boxes today as they did 15 years ago.