I have heard people say that they thought the core set was too strong and there were too many underpowered cards in the sets following. I'm going to argue that the game has actually been proceeding the way it should.
In what has been up till now a non-rotating game, power creep is inevitable. Power creep is when new cards are better than the old ones (usually made that way to excite players about the new stuff), but then even newer cards have to be stronger still. Eventually the old cards become worthless. It's one of the fastest ways to kill a game.
The reason why it happens is because whatever card everyone is using at the time becomes the "new normal" and is soon taken for granted. Take a look at Corroder, people used to complain about it being too powerful, but now no one uses it any more because Paperclip is the new normal. We wouldn't expect them to print a fracter even stronger than paperclip any time soon; but before paperclip was printed, we probably didn't expect anything stronger than corroder.
(You can try to print 'side grades' but with the amount of testing everyone is doing they will quickly find out if the new card is slightly better or slightly worse than what they had before.)
So if it is inevitable, how do you deal with it? The best way in the short term is to make sure power creep proceeds as slowly as possible. You let people upgrade some of their card 'slots' on odd occasion while still needing to keep lots of their old cards. In the long term you can use things like rotation and ban/restriction lists which is basically what Netrunner has done.
I made a mathematical model to try to predict how many core set cards you would expect to see in decks today.
Let's say a deck uses 20 distinct cards. Let's say that every second expansion, they can improve one of those cards to a new card. (Not every single expansion, since they have to make new cards for other factions or other archetypes than what you're playing). However, the same card can be improved more than once - for example I might change Wall of Static to Himitsu Bako, then later change Himitsu to Vanilla. This means each card has a 5% chance of being changed each time.
There have been 36 expansions, which means 18 changes. The chance of a card surviving from core set till now is 0.95 ^18 which is roughly 40%. I would expect that 8 out of my 20 cards from my core set deck are still in my deck today.
Then I checked some modern decks to see how well my model holds up.
Rich Girl Andromeda has
- Account Siphon
- Inside Job
- Special Order
- Sure Gamble
- Bank Job
- Crash Space
- Gordian Blade
The designer said he also wanted a Femme, so that is 9.
2015 world champion corp deck has
- Accelerated Beta Test
- Adonis Campaign
- Archived Memories
- Hedge Fund
- Ichi 1.0
That's exactly 8.
Conclusion: Power creep has definitely happened - you wouldn't have much luck with a Core-and-Genesis deck in a modern tournament - but it is happening at the right rate to keep the game interesting without killing it. There is no need to demand that they print cards of equal power to the most powerful Core set cards in every expansion.