I usually don't visit websites that don't have RSS and tell that to the website owners. You should do the same. How else will they know that people care about feeds?
And feed subscribers are much stickier than most web visitors - you can't generally use a feed without subscribing to it, so anyone who uses a feed will see it again. The problem is that stickiness per se is not actually that valuable (especially when it's difficult to quantify). Feed users are so sticky that they will read everything you post but never leave the site by clicking an ad.