normalizedString/input and string/textarea?

Hello,

I'm still perplex about the differences between core forms input controls.

More specifically, if I want to edit an instance according to types, I 
would consider that xsd:string is not correct for xf:input but for 
xf:textarea.

It is obvious that the carriage return, line feed and tab characters 
cannot be entered using xf:input but xf:textarea.

So, why isn't xsd:normalizedString the default type for xf:input?

Thank you very much for your answers!

Alain Couthures
<agenceXML>
http://www.agencexml.com/xsltforms