Informing trolls that they can now return for another round is not a good idea if you want to remain in any channel for a reasonable length of time. That is enough reason to ban you, regardless of any other channel policies.
Because we are in the Nick!Ident@Host format, where nick can be changed, and so can ident, it is meaningless to ban the ident, just as much as banning the nick.
Hosts can be changed too. Perhaps we should stop setting bans altogether, then.
While it's true that idents are not particularly difficult to change on most systems, not everyone knows how to change their ident, nor is everyone inclined towards spending their time evading bans. Most channel operators will set reasonably narrow bans and then widen them as needed, which is exactly as it should be.
To follow on from that, sometimes bans need to be placed that affect a large number of users; for example bans set against botnets or ban evaders. The removal of such bans is not an invitation for the offender to rejoin, but rather to allow legitimate users to join who would otherwise have been unable. Your script is
was a disservice to those people, as well as the channel in general.
I also believe what goes on in private (such as in notice) is outside channel jurisdiction. I was once banned because I helped a user in p.m. rather than in the channel and foolishly let the channel know. That's another thing I forgot to add.
Channels, particularly help channels, have a level of responsibility to their users. Would you suggest that we did not ban users who sent $decode() worms to our visitors? Helping in private is generally not permitted to ensure that the help given is infact helpful, and not malicious. Again, this is as it should be.
To conclude: Your opinions, beliefs, complaints and criticisms are both irrelevant and largely nonsensical. Enjoy your ban, I have a feeling it will be in place for quite some time.