why properties don't support +=, -= ... operators?

[Andrey via Digitalmars-d]

Hello! I am constantly worried about this flaw, why this bug 
still was not resolved: 
https://issues.dlang.org/show_bug.cgi?id=8006
e.g. in Kotlin I can write property like this:
> class Example {
>     var value: Int = 0
>         set(v) {
>             field = v
>         }
>         get() = field
> }
>
> fun main() {
>     var e = Example()
>     e.value = 10
>     e.value += 1
>     println(e.value)

And it will work!

In D I can write something like this:
> class Example {
>     private int value_; @property {
>         void value(in int val) {
>             value_ = val;
>         }
>         int value() {
>             return value_;
>         }
>     }
> }

That's great, but еhe absence of in-place operators creates 
additional problems sometimes, and using ref I think not a good 
idea, because of inconsistency.