I think I agree with Crazy Cocker Gang - the working lines shouldn't be altered to adapt a dog to a pet market, but I do think that more Working Cocker breeders should perhaps be more open to some of their pups going to
suitable pet homes. Surely not every pup which is bred from good working parents is going to be a good worker in and of itself? What happens to these dogs if they don't make the grade at working?
I think the reason there are so many workers in rescue (coming from pet homes) is because a lot of pet homes don't know they are getting a worker. We didn't (Honey is 3/4 Working, but her Dam looked entirely Show - turns out she was half and half), but we adapted and made sure we met her needs.
I think it's one of these viscious circles at the minute - it can take so very long for someone to get a well bred pup from a reputable breeder (whether this is a show cocker or a working cocker), and for working pups a lot of breeders wouldn't entertain a non-working home. So those people who really want a pup, but are frustrated at the wait, will go to those less reputable breeders, who don't tell them what kind of Cocker they are getting, and don't give good back up. These pups are most likely to end up in rescue...

If there were more well bred pups available, I think most people would want the well bred pup - but then there would be a huge surplus of the poorly bred pups, as no-one would need to go to those breeders.
I don't think there's anything wrong with breeding for the pet market, as long as the dogs you are breeding are good examples of that breed. There are very good breeders of show cockers who don't expect that their pups are all going to be at Crufts next year, but they still choose their matings carefully to ensure they would meet show standard, and with relevant health tests and temperament considerations.
I know it's a very emotive subject, and I don't expect people to agree with me, but the way I see it is that while only the very very best are responsibly bred from, there is going to be more demand for the badly bred pup... whereas if more of the good are responsibly bred from, the demand for the badly bred pup will go down... maybe it's idealistic... I'm glad I'm not a breeder!!!

Going back to the OP.
I think you could probably give either strain of Cocker a good active home... as others have said, Workers don't just need the physical activity, but a lot of mental stimulation... If you are prepared for this, there's no reason why you shouldn't consider a Working Cocker. However as others have said, Show Cockers can keep going for just as long....

If I was getting another puppy at this minute, I would get a show cocker, mainly because I couldn't take the risk of getting a worker who had more stamina than Honey. I would love a (pure) worker in the future, but would make sure I could devote sufficient time to training so that I could be confident of meeting their needs....