Just like they made "Designated Marksman Rifles" just high-end hunting rifles, eh? (At least, that's my read. Then again, I wasn't in a very good mindset when I read War!, due to being in an ER Waiting Room.).
War doesn't have any kind of marksman rifles or hunting rifles in it.
And i dont think it's about ease of system, more about balance, as for example having one SMG that has a DV 2 points higher then normal, would be kinda OP and make it the only SMG worth picking up.
I think it's partly due to the granularity of the system.
SR4, at the core, is based on a scale that only goes from 1 to 6.
That means that a shift of 1 point is a 17% swing. That's pretty heft...a D20-based game deals in increments of 5%, a D100 system, 1%, etc.
[Okay, actually, with dice pools, it's way more complicated than that..rather than 1 through 6 it's like 28% extrapolated over the number of dice, or whatever...it's too effin' early for me to do Prob & Stat equations in my head, so I'm calling it 17%]
While I believe (as I stated) that the designers didn't know much (or care much) about firearms, the bigger reason is likely that the smallest modification that can be modeled by the system is that big honkin' 17% increment.
That's why you have weapon classes vs caliber, and why there's no difference between a katana and a broadsword, and why a 3 in a stat is average but a 4 is an Olympian.
It makes for a quicker, maybe easier system - but quick is a bit dirty when it comes to modeling a system.
I think it fits the atmosphere of the game - SR has always been about the spectacle and the story. A system like CP2020 is built around realistic simulation, and thus you can actually (with the proper sourcebooks) pick a specific real-world round and build an entire weapon around that specific ammunition caliber. But THAT game system is for modeling the exact hit-location of each round, the exact penetration, tracking shock and blood loss, etc, etc, etc...it's a about the nitty gritty, not the broad cinematic strokes.
It's simply the atmosphere of the game system itself. I think the one in place for SR4 makes sense and fits the setting nicely - but if you get wrapped around the axle on the difference between a JHP and a FMJ round, 9mm vs .40S&W, 7.62x39mm vs 7.62x51mm...it's simply too granular to be expressed in the system.
-Jn-
Ifriti Sophist