This happens to me quite often also, it's frustrating. I've mentioned it before only because it happened so many times. Though what gets me is these things are the top rewards more often than not. I like ores and don't mind the RNG, but man it sure is a slap in the face when you are basically saying this resource is worth this much then do nothing but take silver. I just don't understand why it's not done like the ascending where you can rework it again and won't see the same stat again. I mean if you're willing to use the resources to roll again then I don't see the issue.

Yeah AND you only get ONE shot at the reroll. After that you can't roll again. I've amended my original post. They need to add a new Dust type that ONLY re-rolls the Primary Stat and can be done multiple times. 

Hell maybe add a Silver Cost to use additional Ores even. Something, ANYTHING vs. the current system

It's frustrating, I get it. Though with all the frustrating things that can happen within the game, ores aren't even on the radar. With ores atleast I can just shake my head and say "oh plarium, you got me again". Haha.

 Honestly for me it's that coming up on 2 years of playing I've only gotten about 1/3 of the epics available, and I'm now constantly pulling double and now triple of the ones I do have. I get it with rare champions, but I don't know why I keep thinking if I throw down a bit more money on some shards I'll get something different. I'm happy with the few of legendary champions I've received, I'm just saying something is wrong with the RNG if I just pulled the same epic twice in the same week the odds of that happening multiple times with different repeat epic champions. Not once or twice, I'm talking 5 times now with one champion going triple. I Love playing this game and don't mind throwing in some money to build my squad but man it gets to a point where I'd  rather just get a dollar price for a specific champion.