I think there are things that at least reasonable fans would naturally come to expect from a show they've been watching for a long period of time. You, as a long-term consistent viewer, get to know the quality, the style, the themes, the attention given to characters and plots, etc. I think fans are more than allowed to expect quality writing, consistency--things that help the show remain what it's been and true to its form (I'm not, as it might seem, advocating that show not evolve, but that it keeps its standards and "mission", so to speak, keep it's focus and artistic integrity--all other things would naturally, I believe, flow from that, and the fans would reasonably be able to expect the writers to give due justice to their investigation of characters and their relationships, and medical aspects and "mysteries", which are all established as things that the audience should and could "expect" from the show). I think that viewers/critics/etc. can bring up when those kinds of expectations aren't being met, or how they thought the show perhaps deviated from its standard for quality or perhaps have included elements that seem less than fitting, or criticize a plot's structure and why it has or hasn't succeeded from a storytelling perspective--more like concrit for the show. Whining and bitching about ships and whatnot...yeah, that's really not the same, and it's sad that it extends into fandom the way it does.