I have written several times including here and here about the shortcomings of "robo advisors". I noted that these services are unlikely to offer a comprehensive investment management that best meets the needs of investors.
Because of the structure of these advisory services they seldom get an in depth knowledge of the investors financial life,tax situation or even a full picture of their investment assets. They create the portfolio based on a short questionnaire then implement an allocation chosen from a set of models that are "cookie cutter". There is no opportunity for personal interaction with the client to explain the portfolio allocation in depth or to learn about changes in the clients personal circumstances.
Since these services are licensed as registered investment advisors they are held to the fiduciarcy standard of always acting in the clients best interests. Although the services charge low management fees and make use of low cost ETFs, and use long term strategies with rebalancing and no short term trading--all important elements of a good investment strategy-- many are asking if that is sufficient to meet the fiduciary standard.
Those raising this issue include regulators and legal experts as the NYT recently reported
Many of the points raised here are the same as those I raised in my posts