I believe they need to do a fifth season because they didn't bring any sort of closure to some of the characters, at least none I can really remember. I don't recall them giving a proper wrap up or send off for Lestrade or Mrs. Hudson - everything focuses on Sherlock, John and Mary. Rightfully so, but for potentially being the last in the series, it didn't really feel like I got closure on everything.
I think there was too much doom and gloom in Season 4. That's a characteristic of shows like Game of Thrones - not Sherlock. They need to go back to their roots IMO.
I think there was too much doom and gloom in Season 4. That's a characteristic of shows like Game of Thrones - not Sherlock. They need to go back to their roots IMO.