There are plenty of gameplay issues, just follow the major threads on it, we all suffer after the Anniversary update.
The market itself is not broken per se, it actually works as intended. The issue is a basic supply and demand problem (it always has been the case). Too many low-value cards are being given out like candy, but nobody wants these random players. At the same time, there aren’t enough highly sought-after Icon and high-profile cards, causing the imbalance. This is exactly how the game is designed to encourage more pack purchases, which makes sense given the business model (not going to get into the ethics behind it, though).
An interesting way to stimulate the market is the conversion of tradeables into XP for badges. This has created some demand for the "unwanted cards".