It's a sign of nothing of the sort. It could show that lower wage earners have multiplied their income by 10 and the top have multiplied theirs by 100, for example.
At worst they've stayed still, although that's despite the influx of women and foreign labour into the market - that's an impressive achievement alone.
Even if real wages are level, the quality of what you get is so much higher. Don't know if you remember food in the 70's but it was horrific. And cars - you were lucky if a car lasted 20k, now you'd be tinkleed off if it didn't do 200. Look at an iPod vs an 8 track, or a modern tv compared to the bricke you had then. Clothes were as bad as the food, if not worse. Life expectancy wasn't up to much either.
Inflation may have kept real wages level at a cursory glance, but that's because you get so much more for your money now. Nobody lives life as badly as in the 70's now, because a life that brick just doesn't exist in developed countries.