"You're wrong, jackass" is not ad hominem, because no one is saying you're wrong because you're a jackass, they're first saying that you're wrong and then concluding based on that that you're a jackass. Ad hominem is dismissing an argument based on the characteristics of the one making it, and no one has done that.
I know what you mean... I've actually said that leaving out the decimal point altogether and having 210 quadrillion indivisible bitcoins would have been nice. But then you wouldn't get to see articles about dollar parity, dinar parity, etc. right now, when the project needs attention the most.
[Early adopters] stand to make a fortune if the currency were to take off and it seems that would leave us with an economy controlled by a small number of participants, defeating much of its potential benefits.
This is only true if early adopters keep holding onto their bitcoins as the value rises. In practice, only a very few will do this.
I started mining about a month ago, which will qualify me as an early adopter if this really takes off. And I can tell you right now that if the exchange rate were to spike to something like $10 within the next year or so, I would probably cash out all or nearly all of my holdings, on the hypothesis that a correction was coming soon. Anyone who buys now and continues to hold at $10, at $50, at $100, ... and finally cashes out at $1000, probably deserves their fortune for exhibiting that level of foresight, patience, and self-control.