There are vendors I don't necessarily trust, and have never dealt with before. For these vendors, credit cards (with their protection, and the consequent premium) are perfect.
There are other vendors that I do trust and do repeat business with. For these vendors, I detest paying what is effectively a protection surcharge, when I don't need it. This is particularly the case for high value purchases where there is some percentage difference, rather than a small fixed amount. I appreciate the reason the payment purchaser must charge a fee; I just don't want the (protection) service provided.
In this case, I accept that I would take some additional risk, but I feel well enough protected by my country's legal system, when I am confident in the vendor's identity and that the sale would fall under my country's jurisdiction. This is not dissimilar to paying for something expensive by bank transfer to save on costs. This arrangement isn't quite that unusual in the UK, where UK-to-UK bank transfers for consumers are generally free. But this arrangement carries extra admin for the vendor in trying to match up transactions.
So a credit card is useful for some purchases (in particular, international ones, ones where I am not confident about the vendor's identity, or ones where I am not confident in the vendor's reputation). But for other transactions, I prefer to have the option of going direct. Bitcoin would be perfect for that, if it were more widely accepted.