I agree it can be a personal thing (e.g. if you already have way too many), but looking at it from an objective mathematical perspective, I think TCB still makes sense at 0.8p each. I almost always redeem for more than 1p of value, and my lifetime average is 2.63p/avios, although that does include some outliers. Still better than I'll get from a pre-paid Mastercard though.

There's also the subjective emotional angle, where I like to think of TCB credit as a sort of discretionary bonus. I'd rather spend that on fun things like premium travel than letting it merge into my bank account or Amazon credit, where it would probably end up spent on batteries or USB cables...