Nobody trains to fight, they train in case they have to fight and you always train with what you use.
So whether or not it gets used for combat is irrelevant, in fact it's probably better if they're not.
It's better to prepare and prevent than repair and repent. Assuming you live to repair and repent.
That being said it would be pretty silly for someone to buy a Karambit or a Tanto and then end up using it opening boxes or something. So I can kind of see your point. I just don't think there's anything wrong with keeping a tactical knife around. I don't really think they should be folders but Doug Marcaida swears by those Emerson Karambits so who am I to say what someone should carry or why.
There's nothing at all wrong with keeping a tactical knife around. Knives are tools and one of that tool's uses has always been self defense. There are many uses for many types of knives and opening boxes and removing splinters from your hands are very valid uses as well.
I hope I am not being persnickety here. I was really speaking more of the marketing which sold knives for "tactical" use when that use was never going to happen in the majority of buyers. Many will use the knives in that function or train to seriously, and that's great. Still, often it is just marketing to sell knives.
Knives are a tool for me and I would like to see money and effort put into making a quality tool which will last instead of into marketing to move product. There have always been snake oil salesmen I suppose. They can work on a much larger scale these days and quality and durability sometimes are falling by the wayside.