Ordinary users are not going to want to use the command line. Although it is useful for wrappers to use, a non-technical user will shy away from anything done in the command line.
Well that's why there is QSynth, right? (I haven't used QSynth much personally.)
What we are talking about here is unifying the way you tell FluidSynth your reverb preferences, so that {command-line, interactive prompt, network access, API, GUI} all have access to the same set of preferences, and use the same names for them regardless of how they are configured. This can only be a good thing.
And in any case, just because ordinary users don't want to use the command line doesn't mean it shouldn't be supported. More technical users such as myself need to get the most benefit out of FluidSynth. (For me personally, if FS didn't support command-line, I wouldn't use it -- it is too much hassle to manually record all the tracks using a GUI. I have scripts set up to automatically convert all of my MIDI into an OGG file so that I can be sure the OGG version reflects the latest MIDI.)