What else could they be other than securities? That's the purpose they serve.
From Investopedia: "A security is a fungible, negotiable financial instrument that holds some type of monetary value. It represents an ownership position in a publicly-traded corporation (via stock), a creditor relationship with a governmental body or a corporation (represented by owning that entity's bond), or rights to ownership as represented by an option."
That was the design of tokens from the beginning, and they were created for the purpose of being securities.
It should be no surprise that they're regulated as such.
Would it be a security in a future where the world runs on Ethereum and it is used to secure the decentralized network? No.
Is it a security today? That's complicated.
There is a lot of legal discussion in the token space about when the transition from security to commodity happens. Unfortunately the SEC provided no guidance on how it thinks about this question, but lots of people are working hard to figure it out.
From Investopedia: "A security is a fungible, negotiable financial instrument that holds some type of monetary value. It represents an ownership position in a publicly-traded corporation (via stock), a creditor relationship with a governmental body or a corporation (represented by owning that entity's bond), or rights to ownership as represented by an option."
That was the design of tokens from the beginning, and they were created for the purpose of being securities.
It should be no surprise that they're regulated as such.