The whole shtick of the Salamanders (besides the fire-ash-forge-fire fetish) is that they are the most humane chapter, after all--and while sure, an Ultramarine doesn't have to be a zealous, intolerant crusader like the Black Templars, I really think AD-B tapped into something with the "slightly autistic, out of sync with regular humans" view of space marines.
Additionally: Ventris was a chance to make the Ultramarines interesting, and was squandered. The magnum opus of the most brilliant tactical mind in the Imperium, a book tens of thousands of pages long, is (I imagine) going to teach you a whole lot more about warfare than it does tie you up to formulaic limitations. It's not going to be a book that forbids taking the initiative or attacking where your opponent doesn't expect/is weak.
The Ultramarines aren't supposed to be hidebound vanilla marines any more than Abaddon is supposed to be a laughable, mustache-twirling failure. Those are just memetic ideas bouncing around in the fanbase, not the They are exemplars of discipline and crisp tactical flexibility. The Second Founding was entirely based around the Ultramarine principles of the Chapter, and the majority of chapters are directly descended from their gene-seed. You may recoil to hear it*, but Matt Ward was right when he said most chapters look up to the illustrious, pedigreed, honored Ultramarines.
And McNiell's Ultramarine books... are decent space marine stories, but I can't help but feel they don't do credit to that legacy or sense of grandeur. Have only read the first omnibus, true, but still...
*and I agree that last SM codex gave them too much of the spotlight
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!