Pokerlisting’s link is far from useless. I get a few hits each month from mine… but I’m fairly sure I’m getting no PR.
I won’t usually exchange links with someone using PHP redirects, myself, but it’s the webmaster’s choice. As I said, I don’t think every webmaster who does these redirects is unethical or greedy, but I think it’s certainly a common reason.
Also, I doubt most of them are permanent redirects, since whatever page they’re redirecting to may cause duplicate content issues for their website (there’s a large dicussion about this). But perhaps some are permanent. I just can’t imagine a website having hundreds of permanent redirects not being penalized in some way by the SE’s.