I don't recall FRWL being fun and light-hearted.
Really?
The score is, there's a general light mood (contrasting with the impending doom of Grant) and Connery's even smiling in action sequences.
Ditto with Shark and Safari. It's absolutely light-hearted, nearly to a fault IMHO. Way moreso than Craig's outings. It's why I personally rank CR #1 above FRWL. Quite a bit more tongue-in-cheek than the novel.
I'd say to it's benefit to be honest.
The one aspect where the films improved upon the novels is in the humour department.
Sure, sure. Horses for courses and all that. The train confrontation was an improvement as well, for sure. I do love FRWL, don't get me wrong. Watching it these days, though, just reminds me of how much more original NORTH BY NORTHWEST was. The action scenes after Grant's death were fine (though the boat chase is a bit "meh"), but they seemed to be all on top of each other. Again, nearly to a fault.
I suppose I like my humor a little more dry in general, with notable exceptions.
Drier than FRWL?
I prefer my humour to be something like TB's - "I know a lot about women", "Not from where I'm standing", Bond only handing Fiona her shoes, "Could it be the front doorbell?"
That sort of thing.
The "humour" in QOS seems to be both poorly written, and poorly delivered.
Oh, I love that TB exchange, too. My POV is more about FRWL being held up as the untouchable masterpiece it only sorta kind of is. It's not 100% note perfect to me. Love it, could go on all day about its merits, but there are just some moments that fall flat. Just like any other Bond, really. After a particular recent viewing of CR, I found it shocking just how light-hearted FRWL was by contrast. Found it a little disappointing. Again, just me.
I certainly wouldn't call QOS' humor flawless by any stretch of the imagination. My biggest laugh from Bond came at the "Time to get out" line. Very Connery IMO. Also, and I know you disagree, Elvis is hysterical. THE antithesis of the Bondian henchman, emasculated right down to the pants being blown off him in death. He has his following here, and Judo, dino and I will defend him to the death.