Why equals and hashCode were defined in Object?

What's the reasoning behind decision to include these methods in the java.lang.Object? Equality and hashing doesn't make sense for many classes.

It would be more logical to make two interfaces:

interface Equalable {
    boolean equals(Equalable other);
}

interface Hashable extends Equalable {
    int hashCode();
}

For example HashSet definition might look like

class HashSet<T extends Hashable> ...

It would prevent one of the common beginner mistakes - using set of items without implementing equals/hashCode.