It would increase overall playtime, because people would be able to grind old raids to get extra coins for new armor (new chest would cost 24 coins following this model), plus we know people will grind to keep rerolling items (Gunsmith proved that) and this way would reward effort more than luck(making the community happy and willing to put more effort in). I also made this right before bed, and now Actually looking at it, I see a few more things I would change to increase viability of this model (completion coins could be raid specific and separated from raid coins, and used to build that raids exotic, or exchanged for raid coins. That way after "x" number of VoG completions, you can buy a mythoclast, but not a QBB or Nechrochasm. That way you can't just grind one raid and eventually unlock all the raid drops.)