I know what you mean, but it all depends on how you view risk. For many people, if you have a very long investment timeframe and can afford to sit and wait out a downturn without needing to access capital, using strategies like this probably does not make sense as they will, as you point out, generally deliver lower absolute returns than traditional long only equities strategies.
However, if you are concerned about things like sequencing risk, strategies like this can make sense. Traditional defensive strategies like fixed income (which have a lower correlation to equities) are generally going to be generating minimal returns going forward, so lower beta strategies like market neutral, managed futures or global macro, can make sense as an alternative. But it's all about the requirements of the individual. These are not a one size fits all product.0
Also, bear in mind that while many of these strategies have only delivered single digit returns over the last 3-4 years, it has been an uncommonly difficult environment, with low dispersion of returns. A normalisation of market functions without the weight of QE should result in better conditions.
