I'm not sure what kind of connection there is between being boring and being more likely to jump ship. Plenty of interesting people jump ship too, because the best way to become interesting is to accumulate a lifetime of diverse experiences and staying in any one place gets in the way of that.
If you don't want people to leave the business, earn their loyalty. A boring person still wants to be treated fairly. They still want to take vacation, even if it's to visit their boring family rather than go backpacking in Tibet. They still have the same capacity to either enjoy or hate their job. They just don't necessarily have an interesting answer to the question "any plans for the weekend?", and I don't see why that makes them worse employees.
I'm not sure we mean the same thing by 'boring'. Boring, to me, doesn't mean that the person doesn't have hobbies, rather it means that the person is a perfectly nice person who just doesn't gel with the team. In fact, 'boring' is probably the wrong word here: it should probably be something closer to 'outsider'. That said, larger organisations do depend upon outsiders to prevent groupthink, so this is a multi-faceted issue.
If you don't want people to leave the business, earn their loyalty. A boring person still wants to be treated fairly. They still want to take vacation, even if it's to visit their boring family rather than go backpacking in Tibet. They still have the same capacity to either enjoy or hate their job. They just don't necessarily have an interesting answer to the question "any plans for the weekend?", and I don't see why that makes them worse employees.