Did you not have to grind for 4 hours to get that legendary? The RNG gives you the same shotgun (sucks, I have had it happen too) but the grind for the loot to drop is real. Also doing those strikes for 4 hours surely netted you some marks, which you can go to a vanguard npc and buy the legendary that you want. Which is again grinding for marks. I see what you're saying, however the grind is still there, RNG can shit on it, but it still exists.