@Carl Love The first sentence in the Maple help page about RealDomain is
By default, Maple performs computations under the assumption that the underlying number system is the complex field. The RealDomain package provides an environment in which computations are performed under the assumption that the basic underlying number system is the field of real numbers.
What do you get of this sentence?
I just get that if you want to just work with Reals call this package. Of course, if you want to work with the field of Real numbers then you will not be pleased to use assume for every variable.
About the name, you are right! :) I wouldn't use that if the name was like that. However this does not cover the need for such package that ensures that you are in the Real number system.