No. Watchmen didn't need sequels or prequels. The recent "before watchmen" comics are ok, but could've done completely without. TLOU is fine the way it is, fans need to know when to stop asking for more and more until the franchise becomes tarnished by sequels or prequels. What else can they do for Mass Effect 4? You had the highest stakes in ME3 by threatening all organic life in the universe. Anything less in ME4 will feel like a step back, threatening the universe again will make Shepard-and-crew's-efforts/sacrifice pointless.
The way I feel about TLOU sequels or prequels is the same way I feel about the ME3 ending. Fans hated the ending to the game, demanded that it be changed completely, it didn't, but did get some alterations. Even if you enjoy the new ending and try to brush off the original, you can't because you consciously know that it's not part of the developers original vision, and is instead something shoehorned into the story simply because whiny fans didn't like the original one. Even if you try to enjoy yourself through added TLOU sequels/prequels/backstories, you can't because you know that it's something that was never meant to exist in the first place. It wasn't in the original game because the developers never had that in mind, that the only reason why it's there is because of unsatisfied fans clamoring for more and more instead of being satisfied with what they were given.
Going off on a different topic, I think Naughty Dog should stop making games and instead make CGI movies for Sony Pictures. They make some of the best story and cinematics, yet I think their gameplay is very basic. Nothing wrong with it, but nothing special about it, the gameplay bits could've been replaced by cinematics and the experience would've been the same
