Readonly attribute with knockout

[Kristijan]

Any idea why the wrapper for numerictextbox add attribute readonly when I use this widget with knockout binding?
My code is:
<input type="text" class="k-textbox" id="inpNip" placeholder="" name="Nip" data-bind="value: Nip, autovalidate: true" /> As a result I get: 

<span class="k-numeric-wrap k-state-default k-state-hover">
<input class="k-formatted-value k-input valid" type="text" style="display: inline-block; " readonly="readonly">
<input type="text" class="k-input valid" id="inpNip" name="Nip" data-bind="kendoNumericTextBox: {value: Nip, }" data-role="numerictextbox" style="display: none; ">
<span class="k-select"><span unselectable="on" class="k-link">
 In first input is attribute readonly because of which numerictextbox acts strange. The behavior is visible also on knockout-kendo.js page ( http://rniemeyer.github.com/knockout-kendo/web/NumericTextBox.html ).

So any idea why it is like this? How to get rid of it?

Thanks.
/KrisD