Astounding special effects, good acting, but one small problem

Rating: Null/10 (4 August 2005)

I don't know if what I'm about to write would be considered a spoiler or not, so if you don't want to read a note on a specific problem with the logic of the movie, don't read any further.
Others may have already made this point, but, why did they change the basic plot of the novel (and the first movie version) to say that the pods were hidden underground for a million years? That makes the movie totally illogical, as why would they have gone underground a million years before when they would have been easily able to defeat humanity at that time. They could have framed it so that the tripod initially burrowed into the earth when they hit and then emerged a few hours later, retaining the fantastic special effects, but not introducing such an illogical plot twist into what is, overall, a great movie from the special effects perspective, and a decent movie in terms of the acting.