The tick/tock is done for both business and engineering reasons. Debugging new silicon is hard enough without landing a new microarchitecture and a new process simultaneously.
While the ticks (new process) aren't quite as exciting as the tocks (new architecture), they bring real benefits in cost, power, and increased perf, not to mention usually a few microarchitectural enhancements. These chips are the best of their uarch, and they pave the way for the next tock, as you point out.
Disclaimer: I used to work for Intel's Oregon CPU Architecture Team in the performance group, but that was more than three years ago, so take what I say with a grain of salt. And, of course, I don't speak for Intel in any way.