Bash an zsh both copied sh and ksh (88) fairly faithfully on old features. Where they diverged on newer things, bash nearly always acquired the feature later than zsh and only very rarely implemented things in a compatible way. Especially for interactive features, I don't think they've seen any need to be compatible. Zsh made more effort on easing things for old tcsh users. It is only on Linux where bash came to be a "default" – if you want pure defaults, see how you enjoy either early sh or a pure POSIX variant as an interactive shell.
Where differences drive you bananas, a little effort to find the right knob to tweak and to stick with it would be rewarded in the long run as you explore the nicer features at your leisure. I'm guessing the asterisks is `setopt NOMATCH` to tweak or, otherwise to understand the benefits of the zsh default.
Forced it? I've used a custom bash (v. 4) on OS X and not Apple's older bash for a decade or so, and I'm using fish since the last 2 years, not the OS X zsh.
It's trivial to change shell (basically, chsh, as in any Unix).
But there's nothing extremely important about it being GPL3 and not GPL2 (except that it should follow the FSF dictums to the maximum).