What about Nirvana? Or Metallica? I think in the case of "The Beatles" it's clear cut because it sounds like you're talking about insects. But in other cases I think both sound ok because you could either be talking about a group of people, or a movement or a brand.
- "The Beatles are..." This means we're talking about those 4 guys in The Beatles
- "Metallica is..." Means we're talking about the band, not the 4 dudes.
And when that change happens (inferring the band vs inferring the band members) it doesn't change the meaning of the sentence, so nothing else matters.
As non-native speaker I think I'd intuitively go with “Metallica is” and “Nirvana is”, but “The Beatles are”. I guess my brain is more wired towards whether the name itself is plural or not.
What about "Dire Straits"? Also plural, but grammatically completely different from "The Beatles" (by which I mean: you could say that John Lennon was a Beatle, but you can't refer to Mark Knopfler as a Dire Strait)
Dire Straits is something that happens to you, it would be used in this context, 'He was in dire straits' meaning, in big trouble of some kind. The straits in question are not a plural of an individual living thing like a Beatle. So I would say 'Dire Straits is a band'. I'm a native British English speaker, that sounds right to me, but my generation weren't formally taught grammar at school so I can't back that up with any fancy grammar words!
Since there appear to be no right answers and I love this topic, I feel the band's name should play a big role in its plurality. I would never say that 'Queen are a band' but I would also not feel like 'The Beatles is a band'. At gun point though, I'd choose the latter.