Well, this has been an issue since well before Amazon did their PR-motivated about face- and while it sucks that it required the support of big boxes to get moving, I can guarantee you that all the actual mom-and-pops that I had noticed taking a stand (and, being the kind of person who shops at independent bookstores, I can guarantee you I noticed it) were in favor of something like this. That Wiki focuses exclusively on other, bigger supporters is unfortunate.
The Wiki entry focuses on them because they're the ones pouring cash into this effort. I'm sure there are plenty of small businesses who support this too, but those who are leading the charge at the forefront of this are corporate lobbyist fronts attempting to maximize their profits at the expense of consumers and their competitors. This bill really represents the worst of all worlds: Corporate rent-seeking, higher costs for consumers, more hassle for businesses, and concern trolling about "protecting small businesses" (I'm referring to politicians, not you) when this bill is backed by moneyed interests whose clear intent in supporting it is to crack down on small online businesses (see: Amazon).