I had to reply to this, not because I have my own mailing lists, but because I am aware of the Mailman hosting page on the Mailman wiki. I see that at least one of the recommended providers mentioned here is featured on that page.
Personally, I am happy with mailing lists. There has been a tendency in recent years for people to promote the latest wizardry, and I will say that this forum - for instance - is quite nice for what it is, but many of the gadgets sold as replacements to plain old mailing lists have been disappointing, haven't really offered a better medium for discussion, and some of the providers of these gadgets have a habit of disappearing and taking people's data with them.
(I'm a bit surprised that Opalstack doesn't support Mailman given the Webfaction heritage, but perhaps there just isn't the demand, and mail-related stuff can admittedly be a bit of a hassle, too.)