I think your last point is important. I don't think shell script writers should be concerned about Solaris/BSD if they are confident that they will use their scripts only in environments where bash is available.
Sorry, I meant "no one who replied to you knows what you're talking about". Still, that list don't tell much about potential breakages. Are you actually complaining about bash having too many features or are there actual breakages? Please illustrate with examples, not links to tedious changelogs and ad-hominems.
Many people, especially Solaris and BSD folk, don't like bash scripts, and want you to write shell scripts in Bourne shell instead.
Many other people, who code on OS X and deploy on Linux, enjoy the extras bash adds, and only deploy on platforms that include bash.