It's kind of funny that you invoked target date funds when you criticize people for not being sophisticated investors.
I work in the retirement industry, and specifically manage a mutual fund platform. Target date funds were emerging as the lastest and greatest thing back in 2007 when I first started in the industry. Like any emerging asset class, there was a lot of competition between the various providers (Vanguard, T. Rowe, Franklin Templeton, etc.) to establish their funds as the best available and drive assets into the funds.
In 2007, equities were doing very well, the stock market was at all time highs, and there had been steady growth since the tech crash in 2001. So to juice their returns, many of the target date managers overloaded their funds with equities. In 2008, those equities didn't do so well. So lots of people that had trusted professional money managers to maintain an appropriate balance of equities and lower volatility fixed income and cash equivalent assets, found themselves with huge losses.
My point in all this is that it's real easy to sit there and say "investing is easy, just do XYZ". But the fact of the matter is, most people are not equipped to invest for themselves, they do stuff like pull money out of down markets, and invest in bubbles, and sometimes they do all the things we say they should do, and they still get screwed.