I totally agree, if you want to control just Hue this is fine. The way I read it was that they wanted to also tie in unsupported bulbs, using Hue and other Plugins in Event Ghost seems like a way to make it seem like one system.
If the issue is controlling Hue bulbs only, I agree with you. The Hue plugin does everything you would need and a single system is always less complex.
Sorry if I misread this.