Your point is negated by the fact you didnt see all the stuff from season 3-6 that did show they knew where they were going.
In fact there are elements of season two that only make sence after seeing season 5 and 6.
Sure, they might not have had every single line of dialogue and every character locked down, and they had to change a few things due to actors being better/worse/being a shit behind scenes/drunk driving, but overall the big stuff was there all along.
The show got progressivly more sci fi from the 3rd series onwards, I think if you had stuck with it you might be giving a different answer now.