It's important to note that ICOs are a mechanism rather than a financial instrument and it's the nature of the underlying financial instrument that generally influences the legality.
For example if it's used as pre-sale (i.e. currency that will be used in product for a future product) then that's likely legal in most places, if it's used as a proxy for equity then it's likely illegal in most countries (most countries prohibit unregulated share offerings to non-sophisticated consumers).
Although in some cases ICOs might get considered as gambling if the purpose is primarily considered to be for speculation rather than whatever the underlying product is.
not a lawyer but be careful, some "products" like a club membership for example, have been ruled as actually securities
in short, any "product" can be a security if there is even a hint of speculative investment activity (and a motivated prosecutor)
really it is less about logic and definitions...this audience wants to parse things and recompile. in law and moreso in regulatory affairs, it is far more about guiding behavior by carrots or sticks to a particular philosophical/moral/politial/economic subjective end goal
For example if it's used as pre-sale (i.e. currency that will be used in product for a future product) then that's likely legal in most places, if it's used as a proxy for equity then it's likely illegal in most countries (most countries prohibit unregulated share offerings to non-sophisticated consumers).
Although in some cases ICOs might get considered as gambling if the purpose is primarily considered to be for speculation rather than whatever the underlying product is.