They have to make bad cards, or at least not-as-good cards. Both so people can learn and also if every card is good you tend to get power creep.
Not explaining that second part well, but I remember quite a few articles from Mark Rosewater on the subject.
The article can be found here: http://archive.wizards.com/Magic/magazine/article.aspx?x=mtgcom/daily/mr5
. I am obliged to to point out that while most reasons may apply, some simply do not work within IW:
1. Bad cards have to exist to make other cards look better.
He states that this is the most important point out of the list. He offers the example of comparing Volcanic Hammer with Lightning Bolt (MTG's version, if you're confused), both offering the same ability, except that Hammer has a higher cost and less flexibility of play. Remove Lightning Bolt from the picture, Volcanic Hammer looks good. Looks
The thing is, the hard and fast stats don't change. VH<LB no matter how you look at it, and excluding those YOLO players who play badly on purpose, 100 out of 100 times people would choose LB (for a mode which supported both cards). It wouldn't matter if VH even existed.
The whole idea of this was because if you put all the good cards in a single set, people would stop buying the rest, so they had to spread them out. It's not a matter of balance, it's a matter of marketing. The thing is, in IW, buying boosters and trading isn't the only way you can get cards. Sooner or later you would get almost every Common and Uncommon Soulbound from quests and leveling up and whatnot, so this reason has no place in IW.
3. Bad cards help newbies learn from their mistakes.
This, in my opinion, is the worst reason in the list, Magic or not. We don't want cards which exist just for the sake of making newbies learn the hard way, we want cards which offer new possibilities and possibly even change the meta.
And how much impact does it have on a newbie when s/he learns that Masked Initiate is a bad card to run, really?
5. Power levels differ because all cards having an equal quality level minimises the effect of differences in skill.
I beg to differ. Wouldn't eliminating card quality differences amplify
the importance of skill? Unless he meant deck–building skills, but gameplay skill still counts for a great deal for victory.
The rest of his points are legit, at least to a larger extent than they are not.