LOST was a great show during its day, but it has not had the staying power of other television franchises.
LOST never made a dent in syndication (in reality based on the way it was serialized instead of the original self-contained episodes).
LOST never made a dent in post-run secondary sales in DVD box sets.
There was some merchandise along the way (with a great deal fan created).
There were some secondary works, but again it was mostly fan fiction or fan books taking an academic approach to the symbolism and theories of the show.
More importantly, LOST did not create any groundswell for a spin-off or continuation series.
The closest thing was the added short in the box set for Hurley's time as island guardian (which was a lame attempt to answer some irked fans unanswered questions) but fell flat. It would have been possible to pitch a Hurley-Island spin off with Ben, but the reaction to The End made it difficult to understand the need or want to rework a skipped segment as its own show.
LOST did not have the staying power to fans like shows like Star Trek, which continue to have a loyal and hard core fan base. LOST had no fan conventions. LOST had no toy figurine lines. LOST had no movie specials. LOST had no secondary cast series. LOST did not spawn a novel or comic book catalog.
LOST got lost in its own story telling in such a way that there was reasonable way to make future derivative works.
A fractured fan base did not help, either. For those who loved the ending wanted more - - - to continue to connect with their favorite characters. For those who were mad about the ending - - - they wanted nothing more to do with the series. For those who were sad about the ending, they either sit and ponder what could have been or have faded away.
It is like an associate of mine who said he was going on vacation. When asked if he was going some place unique like Hawaii, he replied that he had been to Hawaii once, and he had no desire to go back. Once was enough for him. He had no reason to go back. In a way, when bearded Jack kept thinking he had to go back to the island he really had no reason to go back. In the same way, for many viewers today, they have no reason to go back either.