Because Lars is a lefty, and hed smudge it otherwise
There is a lot of crossover potential, and cards that are good in multiple deck archetypes like Bloodghast (good in aggro and Smallpox archetypes) or Snapcaster Mage also work to fill your quota
Any red deck can make room for a copy there aren't many games where you wont have a good opportunity to fire this off, efficiently answering a creature or artifact
However, Sussman said the prevailing sentiment in the TCG market is for prices to come down
If you do want to attach stuff to your opponents creatures, play auras instead
Redshift, Rocketeer Chief is a really good commander for a +1/+1 counters deck, or one that care about boosting power with something like Unnatural Growth