Yeah, you nailed it. There's a ton of room for creativity while staying canon to the series. It would be really awesome to look back at some of the events that Richard saw that we weren't able to see.
Would be awesome to see Dharma for sure, spend some time with them starting up...there's so much they can do without interfering with the show.
LOST is different for me, and I'm sure for many others, because of how it affected me on a personal level. Sure it isn't perfect, but nothing is. There are plot holes, there are things that aren't answered, but the experience was magical.
While I love shows like Mad Men, Breaking Bad, Fringe, Game of Thrones, etc...none of them have me staying up late reading crazy theories that are often better than what the show ended up being.
There are those same theories for other shows, but there was something about LOST. It just hit all the right chords for me, where I was able to overlook one thing because another thing was handled so well.
Even if it isn't the best show, it's by far my favorite show ever.