I recently decided, for personal reasons, to cut up my check card and go back to the strictly ATM card method. I have a credit card I can use for online purchases, but I prefer paying for things out of pocket over worrying about interest rates and whatnot. I can tell you that since I switched to a more cash-only method, I feel great relief when I see a PayPal option on a website.
Not only does it simplify things, it is a LOT more reliable to know the transaction is handled through PayPal rather than giving a check number/account number/routing number to a total stranger. jrcs3 is right; cart code is hard, and when it's a site I've never done business with before I'd rather not find out that they have not put in the time to do it right.
It can be less impressive to see a big goofy "We Accept PayPay!" logo on the front page of a site. Just like it's unimpressive to see a page counter, or a "passes validation" or any other badges. It's also extremely unimpressive to see typos, poor grammar, and bad clipart.
But I think there is nothing unimpressive about giving customers options that make them feel safer and less inconvenienced. You simply have to have to integrate these choices into your site gracefully so that your site doesn't get flagged right-off as pasted together and amateur.