I remember reading an interview a bit like that, but I guess because he also kept going on about how much he was inspired by Tolkien's worldbuilding, which he didn't deconstruct at all, and indeed, only less intensively replicated, I don't really see it as a deconstruction of LotR, but rather a deconstruction of heroism/character behaviour (specifically) in epic/high fantasy.
I agree.
I haven't read a lot of romantasy, or romantasy-adjacent stuff, but I don't think it was at all wrong to put in the fantasy section. Like, Sarah J. Maas I think is on the borderline, but isn't romantasy, the romance is more of a backdrop, however wish-fulfilment-y, to a more straightforward adventure tale. T. Kingfisher (Ursula Vernon) is clearly romantasy, I remember thinking "Omg I'm reading a romance novel!", but guess what? I finished that book and the first sequel (and might read another)! Because frankly, the world-building and fantasy elements were better than the vast majority of fantasy novels I've read. More interesting, more engaged, more real-feeling even somehow? And without being grimdark!
So I don't think that's a real problem. As you say, genres are flexible, and there's always been a lot of romance and adventure in fantasy novels, it's just a matter of how they lean. Far better romantasy than '00s grimdark rape-obsession, I say! We survived that!
What might kill fantasy as a genre, frankly, is if LitRPG and closely linked subgenres start getting published by major publishers and put on the shelves/recommend heavily by Amazon etc. to people who read fantasy. Thankfully this is not currently the case, and I don't anticipate it becoming the case, given that so far that genre seems to combine "being really ultra-niche/bad-nerdy/head-in-ass" with "having no elements with crossover appeal".