That is not really true. There was a period of (planned) rolling blackouts, but in the end energy conservation (and increased generation) meant that, except for immediately after the quake, the lights didn't go off.
However, many buildings (and stations) reduced lighting and took some escalators out of service. However, even those measures have mostly been abandoned, with escalators and the like operating as before (partly due to the fact that it wasn't practical to block off escalators in many of the busier stations). Many stores and offices, however, continue to turn off some of their lights.
That said, even at "reduced" lighting, most Japanese stations are still incredibly well lit. We aren't talking about platforms half shrouded in shadow so much as a slight reduction in the overall brightness level.
It will be interesting to see, however, what happens as we once again approach summer (and the increased energy demands due to A/C) combined with the current shut-down of nuclear power plants.