FlyerTalk Evangelist
Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: BA Silver, TK E+, AA PP, Hyatt Globalist, Marriott LT Plat, Hilton Diamond
Posts: 13,033
It's one of those trade-offs.
The E+ member naturally would want to fly in the same cabin as their partner on holidays, and may well be flying in J already for business so can't find a use there.
But TK wants to reward the actual member, and probably to avoid account hacking fraud / a secondary market in upgrade certificates.
Hopefully you can upgrade family members using miles instead and use the certificates for yourself...