There are some cards that do have the same effect for different mana costs though:
Lightning Strike
vs
Lightning Bolt
The difference is - as Wizards releases more and more cards, they have a better idea how to balance different in multiple ways. So sometimes, if an old(er) card was really good they might reprint it (with a different name) but change something about it to make it a little more balanced.
Another argument is that cards aren't just based around what they do - but in what block/set they appear in. Sometimes a card can fit the theme of a new set they're making, but to make it balanced
in the standard format they may change a few parts of the card to make it not-broken.
Some examples of changes that can be made to a card are:
- Changing the mana cost
or change the type of the mana cost (a card costing 1 colourless + 1 red mana vs a card costing 2 red mana)
-Changing the numerical value (ie. damage done, number of targets it can hit, etc)
-Changing the type of targeting (target creature? player? both?)
-Change wording (Using "each" or "name a source" instead of "target" such that hexproof will not apply)
-Changing the base typing of the card (ie. Sorcery vs instant)
Most are pretty obvious, but the game is constantly in flux and I
think that Wizards of the Coast try to balance the game more around standard and limited formats rather than Modern and Legacy. Especially because the overall number of cards available in both formats is so incredibly high, it makes those formats hard to make even. :)
And omgazurile, i don't think i've seen anyone whose played magic for that long without quitting for a long whkle. O: