As someone who has had no formal training on SQL Server of any version and was dumped into the DBA world by the business, I can say that the maintenance plans are a very tasty little inclusion.

People are right in that they aren't flexible and that scripts can do more, but they "should" be able to keep your server running along fairly smoothly if you have no idea what you are doing and no time/inclination to delve into its depths (keeping scale in mind here...).

Remember, not every business can afford the services of a professional DBA (however briefly), regardless of how much of a good idea it might be.

Personally, I still don't delve into things unless I need to, it's not my forte. But I am glad that if I need to find a better way to do something then I have already stumbled across a useful community that collectively knows pretty much anything you could every want to know about any version of SQL Server.