I'm pretty sure they don't know what weapon you "really" want. I love scout rifles, they are my favorite weapon, I've gotten about 20 MIDA multi tool drops. I hate pulse rifles, barely ever use them, I've only gotten 1 red death. By your logic the pulse rifle would be the weapon I got more. Hard light and ghorn were the only two original exotics that eluded me during pre TDB and even during TDB. My first 2 weeks of HoW I got 7 hard lights and the ghorn. It's still just a numbers game, but they most likely (won't say definitely) aren't messing with % to screw individuals, but probably are messing with them to make certain weapons harder to obtain.