I know that most already know that this is a badly needed feature, so I just want to make it a formal feedback. 
Most might already know the workaround on this. If not, you can check the following post: [click here.][1]
[1]: Remapping controls
In any case, even with the work around, I think that an in-game feature that allow this function will certainly smooth things out since everyone has their own preference and “need”.
I had some issue earlier as well with the locked controls (before I found the workaround). I found the preset ones tedious and unnatural for me. So, an easy way to change it in-game would be a great addition to it.
And while we’re at it, this absolutely has to be added: support for non-English keys.
Some keys have different characters based on the region. For example, the default quickslot 10 is placed on ‘;’. On German keyboards, this key has the character ‘ö’ mapped to it. Manually mapping it via hotkeys.xml atm does nothing - even though the character is displayed, no action is executed.
PLEASE, make this happen. i hate to use skills with numbers. i like to do it on QWERT and etc 