all valid points, but I think you’re neglecting a thematic angle.
Shapers run to test themselves, to push the boundaries. Decoders are their ‘favored’ ICE; they like the challenge; they want to crack the code.
Criminals are… well, criminals. Hitmen, con-artists, mercenaries… they don’t want to be detected (Tracers), and are just waiting for a nasty piece of ICE to show its head (Sentries) so they can put it down (with Killers). Threat neutralized, continue the infiltration.
Anarchs just want to get in, period. They can be jinxed by a simple riddle (Enigma, anyone?), but they’ll be damned if they’re gonna be kept out by sheer force-of-ICE. They will tear the kingdom down to get to the data, and for thousands of years, there has been one favored tactic to keep people out of places: Barriers.
The Stealth Dogs gave each faction an answer to its anathema. For Shapers, force-of-ICE can be their biggest weakness. Battering Ram is a great answer, but is MU heavy. Criminals have difficulty cracking the code; precious seconds opening that Code Gate could cost them the operation, and Peacock ain’t so fast. Anarchs, well, there is a price to be paid for your recklessness, er, fervor, and that price is coming over that digital horizon to see an Archer looking right at you.