This was actually deliberate because before 4.7 ActorComponent::TickComponent used to do some tick enabling management that ParticleSystem was self-managing.
In 4.7 we removed that management as it was always a bit sketchy and was deeply problematic with blueprinting components so perhaps ParticleSystemComponent could call its Super now … however, because blueprinting of components came online so late we deliberately only made the basic classes (Actor and Scene) blueprintable specifically because we did not have time to go through each class and identify “fun” little issues like this.
Thanks for bringing it to our attention and we will be sure that when/if ParticleSystemComponent is made blueprintable that it is resolved.