I like them. Whenever I write a prestige class, I have in mind an iconic member of that class, around whom I can base all the examples in the text. Similarly, in Wild Spellcraft, we had one iconic wild spellcaster, an iconic pandaemonicist, and an iconic sculptor of chaos. There were used in all the art in the book, and I made sure to include sample stats for them, in case the DM wanted to just toss in a wild spellcaster and see how the players react. Having them around even helped me envision a few new crunchy bits, since I wanted to give some of them their own spells or magic items to fit the iconics. The iconic Pandaemonicist even got his backstory fleshed out into a sample setting in the print version.
So yeah, I like iconics. I'm kinda surprised we didn't see at least one spell like, "Mialee's Vermin Bane" (stops nasty- ugh! spider) or "Nebin's Nimbus Nostrils" (illusory floating nose that acts like the classic mine canary to sniff out bad air), or "Hennet's Leathery Embrace" (a huge ball of leather straps and buckles appear and wrap around the target, squeezing it for damage each round). That'd be kinda fun.
Though, yes, I wish the PHB had included at least 1st level stats for all the iconics.