The emphasis of the thread (and several others before) is on gliders, and the cry is 'make them spend their money so I feel safer'.
Gliders fly in cloud normally only in fairly isolated towering cumulus, with substantial areas of VMC at the same altitude; why fly through these clouds when a minor change in track will remain clear if you feel unsafe? As has been pointed out before, monitoring 130.4 will also indicate the presence (or otherwise) of cloud flying gliders.
A much greater risk is military fast jets (unequipped with compatible transponders) who penetrate cloud in the open IFR under a much wider range of met. conditions and are often not in contact with the unit you may be using for information. They decline to fit such equipment due to 'budgetary considerations' and their budget is much bigger than mine. And an encounter with them is much more likely to spoil your day.
To fly IMC in the open FIR is a choice; to demand that all others comply with a set of rules that they choose (not the CAA) at considerable cost to others to reduce a minute statistical risk is in my view unreasonable. Of course, if you want to start a fund to pay for the equipping of other sircraft to make you feel comfortable, feel free.