There are certain classes of programming and mathematics that really need integers such as cryptography and fields that would need big number libraries.
That's totally valid, but they shouldn't use Node.js if that's a mission critical part of the project. Nobody is saying that Node.js is the holy grail, but I see that expectations are that high.
Really, who cares? Types are important for the programmer not for the compiler. If I know what I'm doing then lack of ints doesn't concern me.