Yea, I'm not an idiot.
Never said you were, just provided a caution.
I'd also like to point out that comparing real-world tech to Shadowrun tech is perfectly viable in many cases. Real world calibers, for instance, compare very favourably to the damage values of the various Shadowrun rifles and machine gun equivalents, and a motorcycle helmet can be expected to still do what a motorcycle helmet of today does, with the possible exception of having HUDs with all kinds of technogadgets (though those are coming, slowly but surely).
As for characters being in better shape than what you are; again, that's an easy comparison to make. Take the scale presented in the book, where STR 1 through 6 represents generally weak through world-class athlete level strength. Where do you fit on the scale? A STR 1 character can easily wear a helmet all day every day and not even be affected by it (takes AV +3 to affect a STR character as per the core rules). To put that into perspective, a STR 1 character can wear Full Body Armor with helmet (+2 AV) with no penalty. It's only when he straps on Mil-Spec armor or similar (where the helmet is +3 AV) that he suffers a very minimal penalty of -1. If he additionally tries to wield a shield and straps on other multiple layers (+3 from PPP kit, for instance, and a riot shield), however, then the penalties start piling up (+3 +6 + 3 for a total of +12, for a total negative AGI and REA modifier of (1+2=3+2=5+2=7+2=9+2=11) 5). Again, it's not that all this stuff is heavy to my mind, it's that if you're not a particularly strong character it'll slow you down. This is represented by the reduction applying to your AGI and REA as opposed to your STR.
I'd also like to, again, point out that I don't necessarily think weight is a good representation of what encumbrance is supposed to represent, it's how much the item affects your movement ability. A big old riot shield, for instance, conveying a +6 AV, would severely restrict the abilities of a STR 1 character, unlike even the weakest Troll (who in real world terms would be comparable to some of the strongest athletes in the world). As someone who races motorcycles I'm intimately (unfortunately) aware of how much a full-face helmet limits your field of view as well as the mobility of your neck, both on the bike and off.
Ultimately, of course it's up to you what to do in your game; again, I never implied otherwise. I just wanted to make sure you'd considered the implications of such a choice, as characters can easily layer on 5+ AV (7+ if you allow Ballistic Masks to be used with Helmets), which means less damage is dealt in combat, and more damage is converted to Stun damage which in turn has it's own ripple effects.
Cheers,
Martin