Why do we insist that a Sci Fi figure line must have heavy weapons at the squad and individual level? Afterall this is Sci Fi - I mean SCI FI - where that itty bitty energy pistol could potentially have the same firepower as a modern day SAW or even an Abrahms tank in plasma energy form.
For me there are four reasons:
1) Tactical diversity. Especially if you play squad level games.
2) Figure diversity - 5 standy abouty figures with the same WTFIT firearm and only apparently different because they have differing degrees of tennis elbow doesn't pop my credit card.
3) Character diversity. The chopper gunner is alway the hard ass of the squad eg Blane (Predator) Drake and Vasquez (Aliens).
4) They are generally just frikkin cool. Admit it, you loved the stabilised M56 rapid fire support weapons when you first saw them on the screen in Aliens (back in 1986...ahem).
Of course, in the far future man carried squad support and heavy weapons may well take various other forms - robotics, heavy walkers, gun drones etc but it's safe to say that there will always be an eight tentacled accountant on Tharg or slimy blue skinned Minister of Defence on Planet Millibrand that will work out the cheapest way of upgunning their soldiers is to give some poor grunt in each squad/pod a bigger, meaner, heavier piece of killing hardware to carry
(supplied by the lowest bidder of course).