I think that while implied odds are based on pot size, they aren't exclusively, and especially when I have a vulnerable but very solid hand that I would have trouble folding in later streets I think a small pot sized bet on the flop just doesn't cut it.
First of all, implied odds is based on the bet relative to STACK sizes whereas direct pot odds are based only on the bet relative to the current pot size.

Overbetting the pot blows away any second-best hands that might call you, INCLUDING draws. We make money every time people take a draw with bad odds. Blowing them out of the pot causes them to play correctly, and therefore they profit and we lose. We want to maximize their mistakes and minimize ours.

I'm assuming since we're checking in the big blind, we're talking about hitting top pair with like K6 on a KT5 two-tone board. Betting twice the pot here will probably blow away any hands you're currently ahead of, and only get called by better hands like Kx, better kicker. Betting big like this naturally also has the effect of bloating the pot size, making you play a big pot out of position with a marginal hand. This is a situation that is always best to avoid.

Your opponents only have implied odds against you if you always pay them off when the draw comes.