The drug companies want more money, and they are going to get it because $500 billion will be taken from other Medicare spending to be used to pay drug companies for more drugs bought by those in the Medicare Part D "donut hole." The passage of Medicare Part D also benefited the drug companies, and less money is therefore available for other Medicare needs.
The insurance companies will be big winners when everybody is forced to buy a policy from them or be fined.
Lobbyists for those companies with something to gain have a lot more access to the Senators and Representatives than their constituents have. Lobbyists invite them to lunch and have face to face meetings. If you tried to contact your member of Congress, you would be dealing with one of his/her employees in a branch office.