Considering how temperamental those lockers are I doubt they’d even contemplate making changes.
Although they were much more reliable last year than before. Much prefer the key and pay per open that the other three parks use. At least it won’t open someone else locker!
The problem with "key" lockers is the keys can be stolen. If it's only, say, £1 per use of the locker, that equates to £1 per "souvenir" for a chav in the form of a locker key.
If Towers then don't change the lock module of any stolen-key locker, but just replace the key, then the locker can be reopened in future with the stolen key. Add to that the temptation to some that the locker will contain some coins from that days usage... the original lockers to the left hand side of the Oblivion entrance back in 1998 were 20p a go & they suffered from stolen keys & vandalism to kick open doors to remove contents / the 20p's from the lock mechanism hopper.