1. The debacle of the ICOs and their treasuries in "panic sell off" mode.
2. The very low adoption of the Dapp. Flagship projects such as Augur rarely have more than 50 users per day and all Dapps together rarely exceed 10k daily users.
3. Scalability. It is increasingly difficult to maintain an ethereum node and implementations to scale (PoS, Sharding, etc) are still vaporware.
most times it is not the fault of the ethereum token to have to go through the challenges stated above as most times it is not foreseen by the tokens creators but then they have the responsibility of coordinating themselves to give a more better approach to their project and make the most out of it