"My problem with 5E is that levels mean literally nothing. A 1st level character is just as strong as a 20th level character."
"What?! That's not true! Here, look at all the differences!"
"Oh, well, what I meant was that 5E has a flatter power curve than 3E or 4E. And we agree it does, so I was basically right."
Which is to say that I find your argument that "well since some of these 3E Dwarves have LA, and some of them are just environmental variants (doesn't that apply to the 5E ones too?), then a list of 10+ is pretty much the same as two options" to be unconvincing and somewhat disingenuous.
Although this is all a bit tangential, since IME it's not like people played a ton of Dwarves in 3E either, or in fact - ever. If there was a golden age of Dwarves being cool that we've now fallen from, I seem to have missed it entirely.
Edit: Also, did someone call "fire resistance 5" a boring feature that has no cultural impact? Where the heck are you coming from with that? Do you realize what a difference that would make? Small fires (torches, for example) are completely harmless! Fire Dwarves (lets call them) could do the Blackbeard thing (putting lit fuses in his beard) as normal decoration. Even larger fires are much less dangerous, plausibly leading to a much more casual attitude about fire safety, and things like blacksmithing become a lot easier and less tiring. It has more potential cultural impact than the majority of racial features in any edition.