You could say that, since design styles come around again about every 40 years, there isn’t any real need to update your design style. You just need to wait around until everyone else catches up.
But it doesn’t really work that way. Yes, 1960s fashion was somewhat based on 1920s fashion, but it didn’t look the same. Colors were similar, lines were similar — but it wasn’t the same. Just as design of the 2000s, while it referenced 1960s design, it still looked different.
The difference is us. We’re not the same. The world isn’t the same. Science has innovated — the bright colors of the 60s are due to innovation in dyes, and the bright colors matched the energetic mood of the 60s. The 2000s faced an world in turmoil, so, even though the colors are similar, they were more muted.
And what happens in fashion trickles into graphic design and home decor. While the 60s were fun, we really don’t want to sit on bright plastic chairs any more. We have picked up the modern lines, but this time around we have reinterpreted them in more sedate colors.
So, while it is good to know your art history, know what trends might be on their way in, do not assume what was “fabulous” the last time around is going to be market approved this time. Keep your “new” eyes open, and think about it.