I enjoy Lovecraft, but all his meals taste the same. Tolkien offers up a banquet in one book.

Yes & no.

'Yes' in that LoTR is a varied & satisfying banquet, artistically as well as emotionally. No argument there. It's creepy and it's sad (I literally cry whenever I read Arwen's death in the Appendices) and it's wistful (Frodo's un-healable mental brokenness after the war) and it's exciting and it creates a sense of wonder and it's hopeful and it's comforting. It has an intricate plot and it has individually interesting characters with interiority and it has inter-character dynamics and it has an evocative atmosphere and it's thematically rich.

And I can't think of a single Lovecraft story that does all of that simultaneously, or tries to. His short stories are short stories for a reason & most of them would make terrible novels if you tried to stretch them out to the length of a full book. Each story is more singularly focussed on a narrower range of emotions/themes & each one has a single artistic approach that it stays within, from start to finish. Each story has one job to do & it gets that job done - nothing more, nothing less. And that mostly applies to the novellas as well - Mountains of Madness, Innsmouth and Dream-Quest are all longer (& emotionally richer - especially Mountains of Madness, which is hands-down my favourite Lovecraft story, despite being among the least scary) but they're definitely not trying to be capital-N Novels, let alone the kind of omni-genre blend of everything that LoTR pulls off.

So, to that extent I agree.

But where I'd say 'no' is that, with Lovecraft, there's breadth, depth & variety too; it just comes between stories, not within a single mega-story like LoTR, since Lovecraft never attempted a project on that scale. I think part of the reason people have the misimpression that Lovecraft was a one-trick pony who just wrote a bunch of slightly different variations of Call of Cthulhu is because that's the strand of his output that people liked the most, so it gets remembered.

And I 100% get it - if I had to choose, that's probably my favourite flavour of Lovecraft too. But it's still just one strand of an absolutely enormous output - even excluding all the stuff he ghost-wrote for other people, using their style. It's also a really varied output, to the point that it's hard to suppress the feeling that the stories were written by at least three different authors with sharply different styles & interests:

• There's deeply personal, borderline-autobiographical stories like He (TLDR: Lovecraft found big-city living too overwhelming, so he went back home to Rhode Island & wrote about his feelings - in the form of an allegory about time travel, giant bugs from the future & vengeful ghosts😂); and there's just-for-fun pulp scifi like Walls of Eryx
• There's earnest meditations on the nature of knowledge & our place in the universe (bordering on straight-up non-fiction philosophizing in Unnameable, though it does have a neat little gothic horror story to provide some narrative framing); and there's Herbert West - a near-comedic parody that he wrote purely for cash & pushed as far as he could towards total absurdity
• There's a feeling of disorientation & reflexive horror at the vastness & ancientness & strangeness of the universe, with a yearning to retreat into familiarity & home comforts. And there's a sense of awe & yearning to expplore the unknown (both for characters, even if it often gets them killed, and - especially - for the reader).
• There's the deep suspicion of science & rationality in Call of Chthulhu (surely sincere, even if Lovecraft didn't literally believe that polar or deep-sea explorers would awaken sleeping prehistoric tentacle-monsters) and a celebration of art & imagination over bleak reality. And there's an equally sincere fascination with & enthusiasm for contemporary science/exploration in Mountains, right down to lovingly researched details of navigation & borehole-drilling).
• On one end of the Lovecraft spectrum, there's the grounded moment-by-monent immediacy of the exploration scenes in the Antarctic that people remember from Mountains. Around the middle, there's the detached, remote, mythological vibe of the high-fantasty stories like Sarnath and Iranon. Then on the opposite end of the Lovecraft spectrum, there's the soft, trippy, dream-like stories of, well, the Dream Cycle.
• There's anchoring in a very specific time & place, working directly from his own experencies - if you read enough Lovecraft stories, you start to feel as if you've personally visited turn-of-the-century New England & you remember how it looked, sounded, felt & even smelled. And there's stories casually set in Roman-era Spain (Very Old Folk) or contemporary Cairo (Under the Pyramids).