Why is there no range iteration with index by the language?

[Q. Schroll via Digitalmars-d-learn]

Is there any particular reason why std.range : enumerate is a 
thing and

    foreach (i, e; range) { ... }
doesn't work from the get-go? I wouldn't have such an issue with 
it if static foreach would work with enumerate just fine. As far 
as I can tell,

    foreach (e; range) { ... }

is being lowered to

    for (auto _range = range; !_range.empty; _range.popFront)
    {
        auto e = _range.front;
        ...
    }

So why cant DMD rewrite

    foreach (i, e; range) { ... }

to

    for (auto _range = range, index = size_t(0); !_range.empty; 
_range.popFront, ++index)
    {
        size_t i = index;
        auto e = _range.front;
        ...
    }

Doesn't seem like a big deal, does it? I'm asking because I 
suspect there's an odd reason I have no idea and I whish to be 
educated.