I think the reason The Lord of the Rings’s popularity endures is because it’s the perfect story for hard times in the world. It’s escapism to a more simplistic world with idealized characters, but it also portrays the struggles of enduring hardships with sincere honesty and empathetic care. This just makes its overall optimistic message about hope and the power of love prevailing even more profound. I notice a lot of other stories have a difficult time striking a balance: they either try to be overly realistic to the point of aimless nihilism OR just completely unrealistic fluff made from a place removed of earnestness - both can leave people feeling empty. The Lord of the Rings manages to perfectly hit the sweet spot between escapism and realism for a story so beautifully from the heart and truly cathartic as a result. It doesn’t simply leave you with quickly fleeting emotions of sadness or happiness, but rather an enduring feeling of wholeness.
My favorite part of LotR is and always will be the importance of individuals making choices to do good. For much of the books, the Fellowship are acting on pure faith that somewhere out there, Frodo and Sam are still going, still trying to make it. So they choose to continue. Frodo wasn't the chosen one, he was the one who chose to do what must be done. Elrond even says that none of the Fellowship are sworn or bound to the quest and may leave at any time. Early on, there are discussions of Boromir leaving, of heading to Gondor, and it was an ongoing discussion up until his death.
There are countless moments in the story where one person made a choice to do good, regardless of their duty or orders. Hama let Gandalf keep his staff for his audience with Theoden. The Rohirrim riding to Pelenor fields chose to "not see" Eowyn and Merry after Theoden forbade them from coming. Faramir chose to let Frodo and Sam go free.
In good times, it's a fun bit of escapism to visit some characters who love so deeply and openly and support each other to hell and back. In bad times, it's a reminder that even if they seem inconsequential, individual choices to do good, to help others, to make the world a slightly better place? They DO matter, even if just to one person.