There are a lot of reasons to want watch the unreleased 1994 Fantastic Four film.
1. It takes the source material at face value
2. Roger Corman produced it
3. FF 2005 producer Bernd Eichinger also produced it
4. Thing is vastly better executed in 1994 than in the 2005
5. We were never meant to see it.
But most importantly, it shows us how far we've come as an audience... and FOX hadn't, at last, as of 2005. Granted, the 2005 Fantastic Four film was inferior in a lot of ways to the 1994 version, the similarities are spooky.
We can only hope that, with the return to form of the X-Men films and rebooting of the Fantastic Four property in 2015, FOX will deliver on a well-executed, shared universe this time.
Looking back can be much more fun than looking forward: