His -2 ability gives you a lot of mana easily (if you have Koth and 5 lands on turn 5, for instance, you can play Inferno Titan and have mana open to stop Mana Leak, or hit your opponent with a 9-point Devil's Play)
But shocklands are apparently an exception to this rule
Wrath effects are a core element of casual metagames, and most often Biorhythm results in the accidental elimination of players rather than a strategic payoff
On top of that, it has a feeling of Syr Konrad, the Grim, which is eternally popular in EDH
So they made it cost two and added that no creature damaged by Incinerate can regenerate this turn. Although this is great for removing those pesky Will-o-the-Wisps and Yavimaya Gnats, due to its cost, I still maintain that it is inferior to Lightning Bolt and with just cause
The opponent is never safe when you have haste creatures in your deck