Thats a good point, just pop them in a earthed case/plastic case and it would be relatively compact.
You say it provides isolation, does that mean you don't need to earth the secondary? I used to think they were Class2, but later found it never said that and so I have earthed the secondaries in thing's i've used them in (hence the ground loop on my hi-fi amp project and since earthing my power supply it has become far less useable). Are they safe to use without an earth at the secondary? They look pretty well insulated and I can't imagine the secondary ever going live in normal use, but heard there is always a chance unless it is doube insulated/class2 or whatever