...And six years after release WOTC still does not fix it (like the lucky feat, ranger class or the abjurer-warlock with the cloak of shadows, The fact that you can use action surge with spells, etc) so I think this is intended or they do not fix it because it could create a backlash.
What makes Divine Smite too strong is that you can choose to use it AFTER the attack roll. Most abilities that trigger on attack rolls have to be used before and this was never updated.
And also you can use it many times as long as you have spells available to continue smiting in the same round. Other features, like rogue´s sneak or monks`furry of blows you can only use once per round
(I.E: a Paladin at 9th level attacking with a longsword can do a total of 10d8 damage (+ str modifier doubled) against a baddie in one round with no save (ie. two attacks at 1d8 [longsword] plus 4d8 [3rd level spell slot] each). If his opponent is undead or devilish that goes up to 12d8 total per round When the Paladin gets improved Divine Smite at 11th level he could deal 14d8 damage in one round to an undead/devil foe– and who hasn’t fought in campaigns where many foes are under that descriptor like Curse of Stradh, Descent into Avernus or Tomb of annihilation?)
