Why do you use methods for queryParser and bodyParser plugins?

I plugged in the queryParser and bodyParser as below.

```
pipe.plug(common.queryParser);
pipe.plug(common.bodyParser);
```

Currently we have to plug it in as 

```
pipe.plug(common.queryParser());
pipe.plug(common.bodyParser());
```

Wouldn't it be nicer to have it in the method I mentioned previously.
