For example, Mycosynth Lattice doesn't allow mana from Vedalken Engineer to be used to cast a nonartifact spell
While unquestionably weaker then the original version, Dracogenius fulfills a different niche in the format, allowing players to play a "fair" version of Niv-Mizzet, drawing cards and pinging away while being less prone to having explosive turns or combo'ing off, thus being better suited to more casual tables and less likely to become the archenemy of playgroups
Arclight Phoenix still gets value when we draw it since discarding it is actually good, but to get the reach of Creeping Chill we want the ability to cast it
So, it's hardly surprising that it's standard card is up there as the third most popular in the set currently
The effect is easily exploitable with cards like Timetwister and Wheel of Fortune to Mind Twist your opponents as you refill your hand
Yours is dirty and dangerous and needs to be controlled