why isnt more "lost" media released?

Sometimes, a piece of media just isn't popular enough to warrant a DVD or VHS release, and releasing it just wouldn't be worth it for the company that produces it. I don't think that big companies really care enough to know if something that they made 20 years ago is lost, and have moved on to other projects.

Or at least, that's what I've been led to believe.

There are numerous reasons why "lost" or stored away media isn't released and/why it was lost or stored away in the first place.

A lot of silent films, European films, and films from the WWI and WWII eras, are lost because at the time people didn't think to archive them, were destroyed during wars. , etc

Sometimes whoever is holding it doesn't have permission to do so, or has specific instructions from the creator not to do so (ex. Jerry Lewis's The Day the Clown Cried).

Sometimes people are holding lost media without knowing that they have it. I remember a story about a lost Charlie Chaplin film being found in someone's storage building in a bin. Someone went to throw it out and a guy stole/bought the film reels from the guy, restored it, and found the film. Some of the aforementioned lost silent films could be in somebody's basement right now and nobody knows about it. 

Sometimes, as they said above, there isn't really a demand for said media if it wasn't popular in the first place. A couple hundred or couple thousand or so lost media aficionados aren't enough to warrant a re-release either. 

And you can't really use The Room in this because it was Wiseau's passion project, that he wants to be displayed and distributed for the entire world. Birdemic and its sequel were cheap indie films that were made and distributed online and in bargain bins. Since they have become somewhat of an internet meme, or "so bad its good or funny" films (like Sharknado) they continue to be available on DVD and online. 

While as explained above, there are many reasons films and tv series become lost, however the reason many existing series are not released is pure and simple the cost involved. When a dvd is made, people are paid for the encoding, the encrypting, the publishing and distribution thereof, and even when it is MOD, the encoding and encrypting is still an expense and that is why not everything is available online, even when putting something online, the encoding is still an expense and that in itself might not be worthwhile to the copyright owner.

Unsold pilots is probably one of the most lost media out there, and the reason is simple, not many people care for it and there is not a lot of interest in it (I know some hardcore collectors but they are few). The reality is that a few times, some production companies tested the waters to see, but for every Mercy Reef, there was Not Another High School show, and the majority of them did not sell well and still don't. If you want more similar items, vote with your wallet, if you want more obscure cartoons, buy more obscure cartoons; if you want unsold pilots, buy unsold pilots; companies pay attention to revenue, and it is simple, if something does not make money, similar items won't be released because research shows that it more than likely won't make money.

thanks