Just read through this thread, and it raises some fascinating points. I really like your defense, Flammifer, of disregarding (at the time) unpublished Silmarillion information when interpreting Lord of the Rings. Coincidentally, I've been listening through Corey's old class on Dune, and the other day I got to the part where he's discussing some poetry, and makes a case for disregarding later-published "Dune" material which sheds extra light on the content. Corey's argument is that even if the later-published material is stuff Herbert had worked out in advance, he didn't see fit to include it in this text, so that's all we should be looking at for now. How does it come across to a first time reader of the book, without privileged information which comes out later? Even if Tolkien had published the Silmarillion in approximately current form post-Lord of the Rings, it would still make sense to look at the trilogy on its own, without reference to other material.
(On the subject of why Tolkien never published the Silmarillion in his lifetime: I've also heard that the orc problem was a huge sticking point for him, and I could believe there were some others. I'd also point out though, as someone who knows a thing or two about authors - and I say this with the deepest respect and affection - it's entirely possible his reasons for not publishing it had just as much to do with petty nitpicks which even the most obsessive readers would've told him, "Hey, lighten up, it's not that big a deal." Everything I've gathered of Tolkien as an author from Corey over the years supports the plausibility of this scenario.)
On the subject of clothes: I agree Tom casually encouraging the Hobbits to "run naked on the grass" and them blithely going along with it are suggestive of both his and their attitudes. But I also agree with Jim Deutch that nakedness just isn't a thing in Tolkien, and I can't quite stretch Tom's casual attitude about it to the idea that he and Goldberry rarely bother with clothes at home, even with the Adam and Eve parallels thrown in. I'm more agnostic about them wearing other things, like flowers and sunlight, as opposed to traditional clothing - that seems off to me, as well, but maybe I just need to give it more thought.
However, I think this conversation so far has missed out on a pretty big fact regarding clothes, which I believe to be highly pertinent. The primary purpose of clothing on humans is practical: protection from the elements (which, even just going by Lord of the Rings material, I think we can safely infer neither Tom nor Goldberry strictly need); the second, social purpose, is modesty, which we've already discussed, including my 2 cents shared above. These are not the only purposes of clothing however, they also serve aesthetic functions: we like them for how they look, or how they feel, or how they make us look or how they make us feel, and similar such feelings they evoke.
Note how the clothing is introduced in Tom's song:
"Old Tom Bombadil / is a merry fellow!
Bright blue his jacket is / and his boots are yellow!"
Yes, it's amusing to imagine Tom thinking 'Right, there's apt to be visitors in the woods - got to remember the clothes so we don't have a repeat of last time,' and I could definitely see that working in a parody. (A good extension would be to have him show up in just the jacket and boots, having failed or forgotten to come up with a sufficiently lyrical way to describe a pair of trousers.) In context, however, it sounds like, more than anything, Tom Bombadil thinks his bright blue jacket and his yellow boots are awesome, and he enjoys them so much that he just has to tell the hypothetical audience for his song all about them. "Hi I'm Tom Bombadil! I'm a very jolly guy, and check out these sweet threads and this sick footgear I'm rockin'. Aren't they just the bee's knees?"
(I could totally see Tom as a someone whose dress choices would throw fashion designers into fits, but he doesn't care because he really likes the clothes and how they fit his style, even if they clash horribly for everyone else.)