Generally speaking the adrenaline dump of fighting, even with blunted weapons (SCA) makes you jittery.
The +8 is purely a balance issue. Anecdote follows from the most recent session of my home game. The anecdote shows how in my experience surviving to close to melee is what balances ranged vs. melee. Generally the damage per hit from melee is high, but against a well disciplined fire team with overlapping fields of fire it is a touch difficult to close.
I ambushed the party (gun-bunny medic, elemental/energy focused wielder, 2H melee meat shield) and 2 low end security grunts with a disciplined fire team modeled on current Marine/Army combat doctrine. During this fight the party made the wise decision to stay in cover. Wall of text and math suppositions follow.
/begin anecdote
All of the attackers were wearing light armor for mobility with low-light and infrared U-frames for visibility. All had 27 health pool and physical acumen of 15 (1d6, 5d4). All were assumed to have 5 small arms and 5 rifles/shotguns. Specialists have 5 in their specialist weapon. All have 2 ranks in pistols and carry a CDEM 32 for backup with 2 spare magazines. NCO provides direction and area suppression. SAW specialist provides cover fire and suppressive fire. PFC 1 carries spare ammo for the SAW and covers the SAW gunner’s location while also providing aimed fire at the targets. PFC 2 is a rifleman, he provides aimed directed fire at the targets. All have a reaction high enough to act on 3 and 6.
NCO: armed with FN3000 with 40 mm grenade launcher, 7 magazines of 7mm, 3 40 mm tear gas, 3 40 mm smoke and 3 40 mm frag grenades. Rifle has a relex sight (+2 past 15 meters) and a laser dot (+2 within 20 meters).
SAW Specialist: armed with a Minimi, 3 belts of 7 mm. SAW is equipped with a reflex sight and bipod (+2 additional when prone).
PFC 1: armed with FN3000 with reflex sight, no grenade launcher, 7 magazines of 7mm, 2 frags and 3 belts of 7mm for the SAW gunner.
PFC 2: armed with FN3000 with reflex sight, no grenade launcher, 7 magazines of 7mm, 2 frags.
The attackers got the drop on the party so were pre-positioned around 35 SIM away. SAW gunner was prone to for a +8 to his attacks (+2 bipod, +4 stance, +2 sight) and had a DR of 13 (DR 7 + 6 for being prone). The NCO was kneeling behind a knee high tree stump for a DR of 11 (DR 7 + 4 for kneeling), he gained +4 to his attack (+2 stance +2 sight). PFC 1 was +6 to attacks (+4 prone +2 sight) and DR 13 (+6 prone + 7 DR). PFC 2 was +4 to attacks (+2 kneeling +2 sight) and DR 11 (DR 7 + 4 kneeling).
The party took cover and managed to survive thanks to the cover and the +8 DR for a ranged attack. Based on the setup above most of the time when the attackers fired into cover they were missing by 1 or 2. Without that +8 they would have cut the party down as that represents an extra bullet per active segment hitting a PC. Since the PCs are wearing light armor still this would make the SAW (1d12+1 +1 for 15 physical acumen) do an average of 3 damage per bullet and the FN3000s (3d4 +1 for physical acumen) doing an average of 4 damage per bullet. With focus fire on one PC that would equate to an extra 30 damage in the first cycle, AKA a kill on PCs that have health pools roughly equivalent to the mooks.
Now let’s extrapolate the meat shield’s likely death while closing. She sprints at 8 SIM and has a DR of 10. My mooks are tactically savvy enough to focus fire, their default behavior is to use 3 dice per active segment to keep their targets down. Attrition is your friend in a firefight after all. When someone with a BFS is charging they would blow their dice wad on cutting her down. At her sprint rate it would take 4 cycles to close with a sprinting attack in segment 3 of cycle 5. In cycle 1 segment 3 the mooks dump their dice into her averaging 16 + 10 for SPL + 8/6/4 for modifiers. Their DR to hit is 26 (DR 10 + 8 for ranged + 8 for sprinting). The NCO and PFC 2 get a 30 so they hit once (26) and barely missed their second shot (32 to hit). PFC 1 hits twice with a 32 result and the SAW gunner hits twice with a 34 result. Cumulative average damage is 22 in the first cycle on a PC with a health pool of 34, that there is a pretty serious wound. Now ramp that up and remove the +8 DR for a ranged attack. All of them now hit three times (18, 24 and 30) for an average of 45 damage. Ranged combat is pretty lethal in AO, without the added +8 it’s more deadly than Shadowrun and Rolemaster.
/end anecdote
TLDR: I’m not claiming that PCs are going to exhibit poor tactics, but it’s a fallacy to compare melee to ranged. Sure melee does obscene damage per hit, but that’s tempered with the difficulty of closing the range in the first place. Against mooks without a ranged attack it’s a perfect comparison, but elite mooks will kill the melee specialist before they can close. By elite mooks I mean folks that didn’t bring a pistol to a rifle fight. Of course if in your game world all mooks carry only pistols it’s a different story. I can do the math later if needed on that.