I agree with your sentiment with regard to the huge number of altcoins that have emerged since bitcoin's arrival, but I still believe there is a core value to cryptocurrencies. However, I disagree with the common statement that that benefit is related to anonymity or privacy. I think the core benefit of cryptocurrencies is in their immutable ownership and exchange - if I buy something with PayPal on eBay I might get a chargeback or PayPal may arbitrarily decide that my transaction was fraudulent.

With cryptocurrencies, I don't have to worry about that. The fact that I can store them in a physical location (e.g. a phone app, on a paper wallet in a vault) is immensely useful - I can keep coins in my phone wallet for sending to friends for shared bills, and don't have to think about whether the company that owns my cash is going to make some bizarre policy change or if they are secure enough to prevent hackers manipulating my balance or crashing the company's infrastructure. There's also a sense of ownership that comes with that, similar to owning physical cash.

I think there's two innovations beyond bitcoin that are necessary to become properly useful instead of just a tech toy: economic stability, and fast transactions. Also, potentially offline transactions if that's feasible. Economic stability would provide the ability to trust the coins' ability to maintain value rather than using them for fast exchange and cash-out cycles (inflationary) or speculation and investment only (deflationary). Fast transactions for synchronous exchanges, e.g. in-person or business sales funnels. I don't know if Ethereum (or any other altcoin) provides these capabilities, but that's just my 2 satoshis.