Depending on the situation, PVP, PvE, if there is a burn, if there is bonus abilities such as bonus damage to oracles, supplicants, hive, vex, etc. Yes. I could make efficient use of many more guns than I actually have. In a single mission or raid it's quite easy to switch between many weapons depending on the circumstances... shotgun vs. sniper, rearranging which slot gets the exotic when you want to use Gjallarhorn, Hawkmoon, etc, this all causes the necessity for extra weapons. Now with class specific weapons... you have to divide them among 3 characters instead of just switching the full set of weapons you have to have your vault split between 3 sets of weapons.