[noggin]

For me it simply, understandble... it can decode it self HD audio formats and convert them to PCM but... no one can (or is whilling) make it passtrough the signal...

Very simple - it's a hardware limitation. DTS HD and Dolby True HD require a higher peak bandwidth in the HDMI Audio stream than the HDMI audio system in the Broadcom SoCs that the Pi / Pi 2 use can handle. This is the same limitation that stops the Pi / Pi 2 handling 192kHz 5.1/7.1 PCM and limits it to 4.0 at 192kHz.

Although HD Audio is lossless compression, it doesn't always compress hugely, so it has to cope with peaks of audio that are almost un-compressed, and as DTS HD / Dolby True HD can carry 192kHz 5.1/7.1 tracks, the HDMI bandwidth required for bitstream is similar to PCM. The gain of lossless compression is in on-disk storage terms (as it provides a useful - albeit variable - bitrate reduction with no quality loss), however it doesn't massively decrease the bandwith required for carriage over HDMI.

The reality is that there is next-to-no 192k 5.1/7.1 content (I have one disk - Akira - with a Dolby True HD 192kHz 5.1 track) - but that doesn't stop the HD Audio formats requiring a higher bandwith than is supported by the Pi / Pi 2.

And don't give me licenses crap... to passthrough they say it's require... but to decode itself... doesn't need it... and that doesn't make any sense... if it was supposed to have licences for that, it would be to decode by itself and not to passthrough the signal...

Nothing to do with licences - hardware limitation pure and simple.

Kodi - and lots of Open Source software in general - takes the view that it is up to end users to ensure that they comply with any licensing requirements I believe.