I think that when most people talk about wireheading, they mean something like "ideal directly stimulated pleasure", which isn't necessarily the same thing as current wireheading. It's quite possible for current wireheading to be flawed to such a degree that not only is it not the greatest possible pleasure, it isn't even as much pleasure as people can reasonably get by other means. While I would want the perfect wirehead, current wireheading is less appealing.