InputMode

current status

inputmode as currently defined in XForms 1.1 is underutilized. http://www.w3.org/TR/xforms/#mode

non-script tokens

Here are the current and non-deprecated tokens that aren't scripts:

lowerCase	lowercase (for bicameral scripts)
upperCase	uppercase (for bicameral scripts)
titleCase	title case (for bicameral scripts): words start with an upper case letter
startUpper	start input with one uppercase letter, then continue with lowercase letters 
digits	        digits of a particular script (e.g. inputmode='thai digits')
symbols        symbols, punctuation (suitable for a particular script)
predictOn	text prediction switched on (e.g. for running text)
predictOff	text prediction switched off (e.g. for passwords)

possible reasons for lack of widespread adoption

long list of scripts discourages implementors from looking at the more basic functionality.
digits isn't as useful as using datatyping and bind. discussed at [1]
xsd pattern is more valuable

potential advantages of new tokens

hard to analyze xsd:pattern for validation as you type, or for allowable characters
some kind of value alteration or search-replacement (e.g., instead of "type your phone number without spaces")