restore the historical cards, there is significant game imbalance
Usually when new decks / years of cards come out, its apparent that time and effort was put into maintaining balance among the various colors. Advantages gained can be mitigated and so on. The loss of many of the historical cards, and to the loss of cards for black in particular, has lost much of this balance. I'll probably refrain from playing black for several months to enable MTG to restore cards / produce new ones to restore that balance. I wish more effort would have been put into eliminating the banned cards people are still playing with due to the bug in MTG that keeps those cards from being fully removed, rather than an attempt to build on an inconsistant platform by adding another method of playing.