The Old Maid wrote: If Aragorn knows that Boromir is useless with a pile of paperwork, therefore Aragorn sends Boromir to fight his wars for him, it would bring too much glory to He Who Is Not Aragorn, and "that is how Tisrocs get overthrown." (Yes, Faramir would talk him out of it, but still, no king needs that kind of headache. So Tolkien killed him off.)
But Faramir didn't die. At least, not in The Return of the King. Or are you talking about Boromir?
The Old Maid wrote: It's partly that Aragorn Fan Club mentality that so irritated the sane book-Denethor. I might have mentioned it earlier upthread, but just because Aragorn knows all about war doesn't mean that he knows much about peace. Elvish poetry, courtly manners, and a famous sword won't rebuild burned-out towns, make the rains fall in a famine, or regulate the money supply. You need a career bureaucrat for that sort of thing. Denethor commented that he didn't want to be the "dotard chamberlain of an upstart" i.e. to do the same job of running the bureaucracy for no glory and no pay.
Just to throw in a thought here -- Denethor hadn't known Aragorn, as far as I recall (but correct me if I am wrong; it's been too long since I read the book ). If I am correct, however, then he may just be assuming that Aragorn is actually an upstart. But he's not. Although he is only a new king by the end of the series, he's old enough to know a lot more than other men who come to power at a much earlier age. If he receives glory, I think it is because he didn't lose hope (unlike Denethor). He also joined in the battle himself, but Denethor wouldn't.
Just my two cents... Sorry if I am missing the point or misunderstanding what you said. This is just what I'm thinking when I read your post.
This is a very interesting topic for you to bring up and one that I hadn't really thought of before.