"lost only gives you a few mysteries at a time, and always wraps up a few before delivering the next batch"

Which mysteries have they wrapped up exactly? Do we know what the island is? No. Do we know why there are polar bears there? No. Do we know who The Others are? No. And these are all mysteries that were introduced in the first season.

Lost is pretty popular and I used to like it a lot, but I stopped watching because the writers NEVER resolve anything of real importance.

Firefly, OTOH, was cancelled before they had the chance to pay off any of their setups.