getters and setters not an lvalue

[maarten van damme]

In my current code I'd like to do something ala:

void main(){
		getsettest test=new getsettest();
		
		test.value+=1;
}

class getsettest{
	int myvalue;
	
	this(){
	}
	
	@property{
	
		int value(){
			return myvalue;
		}
		
		void value(int value){
			myvalue=value;
		}
	}
}

but this gives the following error:
test.d(4): Error: test.value() is not an lvalue

Is there a rationale behind this decision of not translating
test.value+=1 to test.value= test.value +1 ?