>, <, >=, and <= aren't range operators, though; they are comparison operators. So to use them to test for inclusion in a range requires multiple comparisons in combination with logical operators.

Which of these examples looks and reads better?

//using the ~= operator
if 0..<10 ~= i {
    print("\(i)")
}

//using the Range.contains() method
if (0..<10).contains(i) {
    print("\(i)")
}

if i >= 0 && i < 10 {
    print("\(i)")
}

Its also far, far easier to loop through a range with something like this:

for i in 0...10 {
    print("\(i)")
}

than this:

i = 0
while i >= 0 && i <= 10 {
    print("\(i)")
    i += 1
}

Especially because when using comparison operators like in that last example, it is very easy to mess up and use, say, < 10 when you mean to say <= 10.