A: There is! The GNU Gnash player is installed by default, and it supports the Flash file format. Unfortunatly, it's not 100% complete in its support yet, but progress is being made.
Q: Why isn't Adobe's proprietary Flash player distributed on Debian media, such that it is installed by default?
A: You'd have to ask Adobe about this. Their licensing terms forbid it.
Q: Why doesn't Debian provide an installer that fetches Adobe Flash Player from adobe.com?
A: It does. The package is called flashplugin-nonfree.
Q: Why is flashplugin-nonfree in 'contrib' instead of 'main'?
A: Because it relies on non-free software, which prevents it from going in 'main' per the Debian Free Software Guidelines.
Q: I don't care about the DFSG. Why isn't installing packages from 'contrib' enabled by default on my debian system?
A: Because when asked, during installation, you said that the 'contrib' repository should not be automatically enabled for you.