True, to an extent. Just adding it in your olam does not give the convenience of having someone tell you what the particular item comes with. For instance, World Traveler does not make roaming calls free, just a lot cheaper. Lots of people do not use common sense to figure that out, and thus it might be best o have them speak with a representative so that can be explained.
I think that having someone in international add roaming is important for a second reason. This forum is full of people who think it has been added, land in a foreign country and find that they have no service. If this is your first time adding international roaming, have a plan in case something goes wrong. Have the direct dial number for international customer support and a method to call them internationally (other than your non-working cell phone).