To remain objective, we need to see this from a dog point of view.
Is keeping dogs kennelled inherently abusive?
Hardly. Hunting hounds, shooting dogs, military dogs, police dogs, rescue dogs, racing dogs, show dogs - mostly live in kennels. As long as those kennels are clean, adequately sized and weatherproof, with proper bedding, and the dogs there are properly exercised, with 24/7 access to water, there is nothing abusive about kennel life. Horses are fine in stables, sheep and cattle do well in fields or on plains/hills/commons. They are animals not furry people.
Is the life of a racing greyhound automatically inferior to that of the average pet dog?
No way. The average pet dog has a miserable life. Underexercised, crated for long hours, fed on cheap rubbish, unfulfilled in its natural instincts, untrained but abused when it does something normal and doglike, forced to co-exist with dogs and people that scare it, the list is longer than I can spend time typing. Fortunately there are people like us who take more care, but we aren't a huge percentage compared to the rest.
Do we talk about banning pet ownership? Some organisations do. Most of us here would rather educate than punish the good in order to tackle the bad. But a life in animal training shows beyond doubt that we are a punishment-oriented species that would much rather lash out than educate. We have to be taught to be positive.
Most greyhound kennels give their charges an excellent life so far as the hounds are concerned. Where welfare starts to unravel is when hounds are retired to the wrong environment. By coincidence, yesterday evening I met a lady who, having worked in greyhound rescue for some years took it upon herself to see what really went on, as part of her thesis. She worked at kennels, led up dogs for racing, spent time behind the scenes at the track, talked to the vets, went up-country to see puppies being raised, and followed an entire litter's progress from conception to the track. The whole litter is racing now.
I admire that. She says she was shocked to find out all these things she'd been told went on, didn't.