I think part of it is that JF is such a neat comic that it keeps inspiring hope that there will eventually be updates. It's never officially ended, nor do we know the creator to be missing/doing something else/without internet.
For another, Tonja Steele updates fairly regularly, and if something happened to it, that would sort of make things feel final. As long as TS is around, I can look at it and imagine updates of the Fridge.
I've seen a lot of awesome comics come to an untimely end, the latest in my list being RPG World. But I've also seen an update on Sparkling Generation Valkyrie Yuuki after six months of not a peep, which is heartening. I guess it boils down to faith, stubbornness, and interest in a solid comic.
I love the characters, I love seeing their world develop. Jackie's Fridge is in my bookmarks list for a very good reason, and it's just as good if I look at a comic now or a year from now. I may not expect updates anymore, but I always hope.