Of all the things to complain about... I like them unbound that way a considerate fleetie can return one they do not want anymore to the fleet bank. The embassy and I assume the spire ones are bound. Kits are cheap to craft and easy to attain.
If kits are the linchpin in your exchange strategy, you may want to rethink things.
Also since Embassy kits and the upcoming Dyson Sphere kits do bind on characters, there isn't much point in the old kits being suddenly changed to bind. Let people freely use the existing kits as is until they get one of the beefed up fleet kits.