I sometimes think that people choose their characters based purely on the ammount of gubbins they can adorn themselves in. The fixation with Purity seals is one such example.
I don't think anyone in the Imperial Army should have a purity seal. it's just not a pure fighting force- too many non humans in it. like wise the rubbish that hangs from the Inquisition is equally silly. It may look great on a figure but in a real warzone performing the manner of combat that we've seen half of that stuff they hang off themselves would be left on the battlefield.
I watch to see how much various people add in their quest to get the "look".
On one side, I can understand what you're saying, however in my opinion the aesthetics of WH40k are about being so over the top, that you can't see the bottom. And: not every Inquisitor burns to be the first on the battlefield, many of them are actually sitting in an office, reading reports, or having tea with the nobility of a given planet.
And then again: embellishments destroyed in a fight=work for the masses who produce them=living.
On purity seals: imo it's especially important to find the few pure among the many not-so-pure. And even those may get corrupted over time.
As far as I see my costume, I'll still be as puritanistic as hell, compared to illustrations.
Of course when (and if) I'll make my assassin's costume, it won't have any of this schnickschnack.