The insane relative power of 1 drops to the rest of the curve is certainly an issue. The general power balance over the whole game is kinda dumb too. So many cards are blatantly awful for no reason (see: new rogue legendary) that may have an interesting effect but never get used. RNG is OK in some cases but the broadness of RNG in almost every card is too insane. When the RNG is effectively "win the game, lose the game, or do nothing" at roughly equal chances, that's terrible design, and that's what a ton of it boils down do when you analyze it. Rag and Syl weren't too bad when there was no expansion because they were basically the entire RNG of the game, and their effects were also somewhat playable around. Every expansion since has vastly increased the number of RNG cards and the unpredictability and potential of those effects at the same time.
Look at that Shaman elemental guy. That's actually a GOOD card, pretty well designed. None of those effects are overwhelming on their own, and the fact you can chose is the difference between a terrible design and a good one. If it was RNG it may or may not see play and would just be another dumb thing out of your control.
Discover was cited as a good design, still some RNG but with choice, and I would partially agree except the power difference potential for most discover options are still too huge to predict or play around.
So, the power level of 1 drops is too high, enabling aggro to have very few counters. The potential of RNG to be either game-losing or game-winning is too ubiquitous, taking agency out of players' hands. And the power of "interesting" cards is almost non-existent, discouraging people from experimenting with deck design. Oh, and ladder rewards winning and losing as fast as possible, further discouraging experimentation.
So that's what you're working with, I guess.