I don't intend to defend big business here, but I can tell you there's another side - or more.
1. Profits: Each tablet may cost a penny to make, and sell for pounds, but that starts from the second tablet. The first one cost tens of millions to develop usually, and the chemical tesing alone for each compound takes several years and each individual test costs somewhere close to �500,000 to complete by govt agencies. Dozens of these tests are required before you put a drug on the market - no-one wants more thalidomide. That said, companies MUST be profitable to continue.
2. The standard used at the moment to gauge new medicine is for every 1,000 trialled, one will make it to market. AFTER the testing mentioned above and the costs incurred.
3. Many companies are hesitant to launch new drugs as they are being copied in the far east and cheap copies flood the market.
4. There are proven cures for alzheimers etc shelved by companies for the present. The drug will work on the condition, but the delivery system just doesn't exist. I won't go into detail on the reasons for this - google 'blood brain barrier' to try understand the workings of the body and why the drugs can't ge to where they're needed- but until the delivery system is invented the drugs are useless. But you can bet that the first one to get a method to work will flood the market and make a mint