it gives us control and extra information
specific scenario where position counts
lets say we open from the button and get called by the sb and bb.
the sb then acts first on the flop, he bets, the bb raises and we fold our middle pair.
lets say we open from the button and get called by the bb.
he checks and we bet 1/2 pot with our middle pair. he calls
he checks, we check back, controlling the size of the pot.
he checks river and we bet out a small value bet
he bets on the river and we decide to call or fold
a lot of the time it's more subtle than this, but position is very useful, it really just makes hand easier to play, giving us control when we need it and putting other players in situations where they can make mistakes.
lets look at the last hand from the BB point of view
we call a button raise with some decent hand, we call because the button has been raising a lot or whatever.
we check our middle pair and button bets, we call.(we have no idea if he hit or not at this point, likely just a continuation bet right?)
we check again, trying to keep the pot small, and he bets again. (great, still no idea, he could just be thinking we are weak, which is likely considering our line. we fold because we cannot face a river bet)
or we check, he checks back (our middle pair is likely good now, but we let him see a card for free, if there are draws there he got to the river cheaply, damn you position!)
river we can't really value bet much, because he likely has nothing.
so from two points of view with the same hand, we can see how being in the BB can lead to mistakes, and mistakes cost money in poker.
hope those rambles help you to see how important position can be, it's great, it can however be overrated at times, you can't just go crazy and play anytwo just because you have the button.