The reason this rule has been added is because too many people are asking about prices for commons, and pricing is too time consuming to price out cards of these rarities when the vast majority of these are worth less than fifty cents
Stuff like Snuff Out or Dismember are already heavily played cards, but here, you get to draw a card from them because you lost 4 life, and you also get to drain your opponents for 2 life, offsetting your life loss
Normally, a big part of the problem with discard spells later in the game is how often they can become dead cards
You could organize events and occasions like birthday parties that are based on the theme of Uno
Magmakin Artillerist is btrasically the only common that truly rewards the discard theme, pinging your opponent every time you loot or cycle
It is a Colorless card illustrated by Uninori