I totally agree, at a minimum it would allow a wireless cylinder stat linked to the Tado system whereas currently you have to use a traditional dumb wired cylinder stat. It could ideally also provide precise temperature control whereas traditional cylinder stats only provide 'call for heat' level control.
However the lack of progress on providing a cheap simple room stat to override unreliable Tado Smart TRV sensors despite many, many votes (234 votes at last count) and requests does not lend a lot of hope.
The crazy thing is that such devices would mainly re-use their existing technology and provide additional sales opportunities.
PS. @PhilipJM you should add your vote to this request.