Depends how you look at it. United's UK website offers lwo season cheap-ish fares booked in H class if you reserve a couple of months in advance. In a couple of weeks, I'm off on a holiday trip LHR-ORD-DEN-SFO-LHR and will be trying out the standby upgrades. There is a decent chance that I will manage to get upgraded at least one-way on a GBP400 fare. And if I don't then I've lost nothing.

In August I'm off to SIN and AKL, again in economy, on NZ, booked on an H fare (cost around GBP850). Again, the upgrade vouchers will come in useful, and if I don't get the upgrade I've lost nothing.

Then there are all the business class flights I take with work, where I will be trying to standby for F.

I think it's not a bad deal (unless you're using the vouchers on BD transatlantic to get an upgrade to New Economy). I didn't expect or ask for the vouchers. Restricting them to H fares and above should mean that there will not be a horde of people trying to use them, which gives me a decent chance of an upgrade simply by paying GBP100-200 more for my ticket than the cheaper V and W fares typically available.