I hope this idea has not been forgotten or at least is still considered... To be honest, this is one of the three reasons that prevent me from fully migrating to the service. The other two could be the adoption of multilingual description and a better application (the latter not very important, but a reevaluation would be good).

The new season of an anime was out, didn't received a notification of related anime, ova, etc (at least from the app or mail)

The major problem is when a new "season" is released, how I would know about It if It is in another 'section'?

Many users use metadata sources or agents that do consider contiguous anime series seasons (ex: thetvdb, plexTV).

Currently integrations with apps that function in this way is spotty at best, because it fails when the SIMKL method (drawing from anidb) disagrees with the season based method the services above use.

If SIMKL were able to translate between the two systems would be very valuable, and allow me to recommend this to friends whose libraries currently make SIMKL very spotty to use.

Where would the data for such a bridge come from? If nothing else, I would be glad to manually enter season/show links for all my media to make this work. Allowing community contributions ('paste the thetvdb season link associated with this show in the box!') might work!

Allowing differing directors/studios and ratings for individual seasons seems possible.

Many users use metadata sources or agents that consider contiguous anime series seasons (ex: thetvdb, plexTV).

Currently integrations with apps that function in this way is spotty at best, because it fails when the SIMKL method (drawing from anidb) disagrees with the season based method the services above use.

If SIMKL were able to translate between the two systems would be very valuable, and allow me to recommend this to friends whose libraries currently make SIMKL very spotty to use.

To address DJShy's concern, on thetvdb each season has a title/name, allowing that information to be preserved.
Allowing ratings for specific seasons seems possible as well.

Where would the data for such a bridge come from? If nothing else, I would be glad to manually enter season/show links for all my media to make this work. Allowing community contributions ('paste the thetvdb season link associated with this show in the box!') might work!

They do...
If you can't do that then at least we need something that will notify you when directly/indirectly content is released/will be released...
Off-topic: Why s1 and s3 are Indirectly related ??? shouldn't they be directly related ?

Combine anime series together like the TV section... pls

I like this idea *in concept*, but considering how lots of animes tends to change the name between seasons, and sometimes even inbetween seasons (I'm looking at you, SAO), this seems like one of those multilevel issues that, as I see things, priorities should be in order and fixing the naming issue is the first thing.

TL;DR: There are other issues with anime seasons that I feel should come first.

Some anime have different producers and studios working on the franchise sequals

if the second season was worse, you will need a different rating for each season
for example, s1 of psycho pass was a masterpiece
s2 was very disappointing

I have the same problem with some anime series
but to combine seasons like IMDB is not the best idea because not all of them have the same quality, for example, diamond no ace s1 was amazing unlike s2

Combine anime series together like the TV section? Currently the animes are different entries. When i import my Trakt data it does not register the different entries therefore missing some episodes etc.

like attack on titan