mercule: Here's an argument for it: The ranger is not a specialist in straight-up combat. That role belongs to the fighter, the paladin, and the barbarian, all of whom are much better built for it in general. The ranger is a skirmisher, a guide, a tracker, a scout, an irregular. Those people DON'T have the main combat endurance of FIGHTERS (who, as their name implies, are fighting specialists) or other characters designed to stand fast and trade blows with the enemy.
To give Tolkien a spin, I'd bet Boromir gets a better Hit Die than Aragorn, even though Aragorn is of the royal house of the Dunedain and a (pretty direct) descendant of Elros; principally because Boromir was a hale-and-hearty, upfront fighter-type, whereas Aragorn had da mad skilz and a host of other abilities that made him an excellent runner, tracker, and woodsman (I'm leaving out the "hands of a king" and other qualities that are probably more about ol'Aragorn being a Numenorean and of royal blood).
Most of the things you quoted, mercule, are issues related to Con checks and Fort saves. On some of these (resisting torture, privation, and traps) I could make the same arguments for why the monk should also have d10 HD. And, IMHO, the ranger should have a high Con. But hit points? Those are the domain of the front-line fighter, which the ranger is NOT. Want a truly hardy meat shield wild warrior type, like a Celt or Northern German? Then play a barbarian. The ranger is a skirmisher who relies on his wilderness lore, knowledge of the terrain, stealth, and hedge magic to squeeze out the advantage from combats. He's NOT a hard-bitten in-your-face hand-to-hand combat monster.
Note, of course, that the ranger does have the same Hit Die as a professional soldier; those are "warriors" in D&D parlance.
Now, if you want a character that's BOTH, the approach to that in D&D is to multiclass and get some fighter levels too.