I frequently hear or read comments disparaging the use of drama, video, special music, solos, etc. in worship assemblies as being inappropriate because they are entertainment. In my experience, the intent of the use of any of these is to communicate with the listener - to convict, to motivate, to instruct, to illustrate - much like an effective preacher. The intent is not to entertain. Jesus told stories - we call them parables; the intent was not to entertain.
When Paul instructs us in Ephesians 5 to "speak to one another using psalms, hymns, and spiritual songs", he is talking about how we should live. He is not talking specifically about the assembly, but that is one of the occasions where we have the opportunity to speak to one another. The singing of a solo or presentational song can be a meaningful and effective way to speak, and may be more faithful to Paul's instruction to us than our insistence on acappella singing in the assembly.