It therefore seems that paper-based redemption methods are more popular than ever, but that ecouponing hasn't got the mass adoption it should have.
Here's a couple of possible reasons:
The major supermarkets have so far failed to embrace digital vouchers. Even my Tesco Clubcard app on my mobile phone, which uses a simple bar code shown on the screen, only works on a limited number of their scanning tills (and none of their smaller local stores near me, which seem to be the type growing in number right now). Yet I walk in with a handful of paper - based ones (from newspapers, magazines and even self-printed at home via sites such a supersavvyme.co.uk) and they all bleep through with no problem.
Perhaps as a result of the point above, even the major FMCG brands (typically the early adopters of these sorts of things) have not taken up the opportunity to use electronic coupons in any sizeable numbers.