Q: Why is using an online service like Ancestry.com better than me simply travelling to libraries, state departments, individual sites and doing Google searches? What is the value in using a paid service instead?
A: Because I can't travel to repositories in my pajamas.
I think it's important to remember that a paid subscription site is a repository. It's essentially the same as going to a library or archive and using the records that are in that one repository; the main difference is how you access the contents. Ancestry's subscription fees are much cheaper than the travel costs would be, if I were to travel to a big library in a different town. On the other hand, if I were at the big library, I might find more records there than I can find through Ancestry; there are many many things which are not available online. The value of any repository, online or real-world, is in knowing how to make use of the collections which are available.
What you won't get at a real-world repository are all the social-networking bits of Ancestry. The message boards, the online trees, being able to connect with other researchers. Those things are not necessarily good, because if someone goes astray and makes a bad connection in their tree, and a dozen people come along and copy it, a new Ancestry user is likely to say "a dozen people have this in their tree so they must be right!" -- not realizing that they have all copied the mistake from each other. But they can be good if the user knows how to use them effectively. The difficulty is, most people don't make effective use of the tools which are there.
What can be gained from a website such as Ancestry.com is something that a user can do without a subscription. Reading the Learning Center articles can be done for free, and even if you decide not to subscribe, you can learn a great deal about what records exist and how to search for them. My advice for anyone considering any paid service is to see what can be accessed for free -- not just the record collections, but the help center articles. Read their advice on search tips, practice with the free collections, and learn how to use the system. The decision on whether to subscribe ultimately depends on coverage for me; if they don't have records for the area I am studying, there's no point in my paying for it. But learning new search strategies, and understanding what records were collected and why, is always useful, because I can take that experience to another site which does have the coverage I need.