In my opinion, shotties are fine where they are. That is not what's broken. What IS broken is the fact that while Bungie reduces DPS at further range, they don't increase DPS at closer range. Shotties are a close range weapon and should therefore be extremely dangerous to use. At premium shotty range, it's a one shot kill, the same should be true for let's say a scout rifle. Scout rifle x does y damage at z range. That dps needs to be upped in increments of 10% for every 10% of range reduction. Use a shotty? OK, better not get hit though, because now my scout rifle that does 30 dps @ z range now does 300 dps at closer range and is also a 1 shot weapon. It's the relative impunity of using the shotty that breaks the mechanic. The risk/reward scenario is entirely skewed in favor of the shotgun.