In reference to the unique structure of this spell, it deals 10d6+40 force damage on a failed save, meaning the average druid beast shape has to save or die, a mechanic that seems to be removed from 5th edition concerning magical spells.
To claim the penalty is virtually non-existent is a failure to appreciate the unique health situation of the majority of druid shapes, as well as to appreciate that it is pretty much a one shot mechanic that not only kills them, severely cripples the chance of them being resurrected in the future.
If you believe the spell is meant to screw druids up (and anyone else who can shapechange) but I would be much more inclined, were I in need of doing so, in treating a shapeshift as a creation of magical force, and applying the mechanic that disintegrate merely removes the shapechange, forcing them back into regular form as per the third part of the spell. But again, you could decide to argue the druid (or anyone else who is a magical creation, including any creature created entirely by magic) is instantly vaporised as per the spell description, but to do so would be a serious failure to apply the spirit of the law.