Umm things. First off, Y1 activities have a chance to drop exotic weapons from Y1. This is correct. The reasoning for this is because bungie added the three of coins to Xür's inventory, they changed it so that strikes and some other activities that aren't raids or nightfalls would no longer drop exotic items. As for the differences in difficulty, bungie hasn't really set a whole lot of guidelines for how long or difficult strikes and story missions should be, as a result you can have vastly different times and number of kills between strikes, for example the old sepiks prime strike, you could solo it and get 90 or so kills during your run of just killing the enemies on the strike. Compare that to omnigul, where I rarely see the total number of kills being less than 200. Unfortunately, destiny has never been a game that will grant increased rewards for specifically more difficult encounters. The game is set up so that it sees you did a strike, and gives you a strike reward, regardless of how difficult the strike was or your own contribution to the team. Same concept with crucible, except being on the winning team gets you slightly more rep.