I was thinking about the possibility that they didn't go with extending the previous adventure because there are a lot of DMsGuild product that does, but then I thought: "So buy THOSE (the good ones) and use them!"
I honestly think that one of the worst things about this adventure is that, while I really enjoy Cthulhu-esque adventures LMoP was NOT the product to kick that kind of story off. It's generic PG fantasy Save-the-Town was a Feature, not a Flaw. The heroism should have been kicked up a notch at higher levels, but it really didn't need a Tonal Shift.