Yea, Joss was hoping for a long run with the series. Revealing everything in the first half of the first season would not have been a great idea.
I am guessing you don't like Lost either, considering that show has taken 4 years to explain most things. And there is still alot it hasn't!
Actually the poster was talking about character, not plot. On Lost even from their 2nd episode each story focuses on some character and the changes with that character. Now the plot, is a different story, but that isn't the problem the poster is complaining about.