Firefox comes preinstalled on most Linux distros, and it's a major PITA to get Chrome working correctly (you have to reinstall flash player, of all things).
It's because the Flash installer (or package manger you're using) only installs the plugin for found installations of supported web browsers... eg.
1. Install Firefox...
2. Install Adobe Flash. The installer/package manager only sees Firefox installed so only installs the flash plugin for FF.
3. Install Chrome.
4. ???
5. Profit?
Seriously though, Flash and Java are pretty much standard web browsing components, why doesn't every modern web browser bundle them by default? I mean, yeah, include an option to uninstall the extensions if the end-user so desires, but bundling them would be a nice touch.
Software Licenses. Adobe IIRC doesn't allow bundling in that manner... And I would have to question Java as a plugin for a web browser these days for the general populace. (Enterprise needs Java plugins due to the many devices that use Java Applets for C3). I'm not aware of any day to day item for a general home user that would require Java in the browser. (Except for those that deal with Banks that use Applets to interface with the banks systems).
Anyway, Oracle doesn't allow anyone to deliver their JVM other than themselves. (Hence why most Linux distro's give you OpenJDK and not the Oracle JDK when you install Java from their repository). If you want the Oracle JVM, you need to install it yourself.
Also from a security standpoint, the less software exposed in such a hostile environment as the WWW, the less plugins you are running by default the better... How many home users have been hit hard due to certain configurations being extremely lacking security wise, simply to make the user experience more dumb, oh, sorry I meant user friendly? (And Yes, Flash, Acrobat and Java have all been major influences in this matter).
PS. C3 = Command, Control and Communications.
Also out of interest, you mentioned Chrome over IE on Windows? Does Chrome take advantage of the sandbox and lowering of user privileges that IE does when running on Windows to help mitigate against malware?