Over the years there have been several bugs questioning the fact
why "Flight of the Amazon queen" and "Beneath a Steel Sky" were
accepted into the main section of the Debian archive by FTP masters.

First of all, both FOTAQ and BASS are fully DFSG compliant. All
the rights mandated by the DFSG are satisfied by their BSD-like
license.

The contrib section of the archive is meant for code which requires
out of archive tools to compile program source, e.g. a library
not packaged or a non-free compiler.

Both FOTAQ and BASS do not need to be compiled, they are a
aggregation of media which is interpreted by free software in
the archive (scummvm).
If they were licensed under the GPL it would fail the "preferred
form of modification" requirement, but it's BSD-like license
grants you all the necessary rights to modify, use and distribute.

While there likely was, once upon a time, a custom set of tools
to create this game data, those tools do not exist any more.
The original creators of the game is in the same situation as
Debian's users when it comes to modifications.

Also, the reason for requiring the "preferred form for modification"
is to not put the creator of the software/data in a "monopoly" 
situation.  This isn't the case here.