Edited: 8/1/2014 9:23:28 AM PermalinkIt is designed this way so that you can't be surprised by a situation, and instantly switch to the perfect heavy weapon for that situation. There is a simple way to overcome this. You mentioned in your OP that you plan ahead and take a Sniper and shotgun into the wasteland. All you need is a bit more planning, and take several Special Ammo synthesising packs with you. This way when you want to make a switch you can get the ammo you need. EDIT: Also, with the amount of weapons you can carry there really is no "choice". You can carry a Sniper, Shotgun and Fusion Rifle; plus a LMG and Rocket Launcher; plus one of every type of primary weapon. You are not making a choice about what you 'might' need. If the ammo carried over, the game would be ridiculously simple.
Have secondary weapons retain the ammo you picked up for it while it was active after a weapon switch in Story and Explore modes. The ammo loss when switching secondary weapons was the only thing that slightly bothered me about Destiny everything else I think is damn near perfect as is. This kind of breaks story and explore mode for me. If I choose to carry an Auto Rifle, a Sniper and a shotgun because I am traversing a wasteland where I may need to make a long range shot, and then have the shotgun when I am rushed by hive in a dark room and an auto or scout rifle for more manageable situations then that is the choice I made. If people are worried about PvP then just only let the weapon you have selected in the Primary, Secondary and Heavy weapon categories enter into PvP. Otherwise I do not need 10 slots for weapons, just make every weapon I pick up through the game go straight to my vault and make me trade it out when I am in the Tower. 1 primary, 1 secondary and 1 Heavy. Having the ammo you pick up for each gun stay helps, I have no issue with the fact that it only drops special ammo for the secondary weapon I have active, that is fine, I like that, but the ammo I already pick up, in story or explore mode especially, should stay in the gun when I switch weapons until I empty it by shooting it. If I am out on a hunting trip and I switch from my scoped rifle to my shotgun the ammo doesn't magically disappear, and I will not carry 50 or 300 rounds of ammo for a weapon I did not bring with me either. For me having the ammo disappear kind of violates a sense of "reality" they have brought to the game.