When Karl Marx wrote Capital in 1867, he said capitalism would never be able to get rid of credit bubbles, financial crises, high unemployment etc. He said that over time the problems would get worse and worse with greater and greater financial crises. Here we are about a century and a half later and you just have to look at the housing bubble, the bank crisis, TARP and the government bailout, unemployment in the US…
Looking at your example, it fails to explain why wages rose for 200 years before the alleged stagnation hit (sure, you can hack some Leninist stuff on about imperialism, but it's mostly unconvincing). Worse, Marx's grand scheme of progress is pretty flawed: even in one lifetime, people readily shift to and from one economic system to another, and each system relies upon and coexists with its predecessors and successors.
Wide swaths of life and economic activity aren't subject to what Marx described as capitalism, and as capital increasingly tries to squeeze more and more value out of people, people increasingly shift to using exit as a means of liberation. Look around you, and you can see it: that's what's most marvelous about the era we live in.