Do they? I always saw them as an alternative to a traditional advisor which can be 1%+ of assets. Even Vanguard can be overwhelming for some people who have to make choices on allocation[1]. For someone who wants auto-rebalancing and a set it and forget it manager, .25% isn't all that much. Obviously if you want to manage the money yourself you can always open a TD account where most of the ETFs used by Wealthfront/Betterment can be purchased commission free. But then the user is left doing buys, rebalancing, etc...
[1] For a complete no-brainer solution open a Vanguard account and dump everything into one of their target funds. Some people want something between the target fund and managing their own though.