No. Absolutely nothing will change. Declining is not a valid negotiation tactic when you're dealing with literal billion dollar companies. Are you seriously suggesting some company like Amazon is gonna change their terms if we decline them? They couldn't care less about us. Maybe if you're a rich corporation using their services. Sometimes not even then if the horror stories I've read here on HN are to be believed.
Where I live many of these contracts are actually in violation of consumer protection law. I've had actual lawyers tell me I can safely ignore many clauses because they are clearly abusive and judges would strike them down in court. Particularly unacceptable are those that make me give up my rights. Appatently that's a thing in the US, you can just sign away rights such as reverse engineering or even the ability to take companies to court by "agreeing" not to exercise them.
If more people did things differently in this fashion the world would be a very different place. Too bad this doesn't happen and the users who actually decline make up less than 0.01%, probably below any error margin.
People just don't care until they personally get a kick in their face. We all know that and companies bet on it.