Oh, dear lord.
Graham, I've trained for decades in aikido and never had a significant hit to my hands training without tsuba. I've also trained with others in other styles as well as people in traditional sword arts. Some of them train with tsuba. In some of those styles I would have received serious injuries to my hands had I *not* had the tsuba in place. Because they do things differently. Not just techniques, but how they train.
The bottom line is that is just depends. It has nothing to do with laziness. Maybe in your astral plane it does, but in my experience nothing could be further from the truth.
Keith. Severe injuries? Sounds like bad training if that's the case.
I have no doubt you have done what you say and thus that is your experience.
I suggest you too read what I said again.
There are times and places where it would be 'helpful' to use a tsuba. Limited. Your example fits to the degree that you din't know or have the experience of that particular sword art.
Bottom line actually is it can and ususally does lead to complacency whether consciously or subconsciously. Unfortunately if you always train with one then one day you won't have one and only then will you understand what I mean.
Reality my friend.
Once again I pose a view where people have to look at something they haven't considered before, ie: the downside of so called protection.