Everyone should just face the fact that most drivers are out there to collect a paycheck. I think one of the few ways that drivers will go for the win more often would be for NASCAR to reduce the cash winnings from 2nd place to 43rd place by a large amount and give the money that was taken away from those positions to the winner.
If you took too much money away from the bottom of the field, about 5-8 teams would probably stop being able to show up each week. That would not be good for the long-term future of the sport. Most of the lowest-tier teams are just barely scraping by now as it is. Some of the start-and-park teams have become more competitive teams over time, once they saved enough money to finance their team (FRM stands out). They also usually give an up-and-coming driver their first chance to start a Sprint Cup race (Keselowski, Dillon, Larsen, etc).
Besides, the top-tier drivers make so much money in base salary, that even a drastic change to the weekly purse distribution wouldn't really affect them. The drivers don't actually win $300,000 for winning a race. The car owner does. How much the driver actually gets out of that prize money is dependent on his contract. I doubt any driver's pay scale is public knowledge, but I can't imagine that even the best drivers get much more than 40-50% of the prize payout, even when they win the race.
Making the Chase is worth a lot of bonus money to the team and driver, so the drivers won't risk missing out on a $5-10M bonus for making the Chase, just to win an extra $50,000 at Richmond. This is why the MWR team was doing everything they could to get Truex in the Chase at Richmond, and no other team tries in every way possible to steal a race win. The real money is in the Chase, not in a single race win (outside of the Daytona 500 and Brickyard 400).
If the drivers didn't earn such high base salaries (or huge bonuses for making the Chase), maybe a higher race win payout would encourage them to try a little harder to win the race. Under the current system, there just isn't much motivation to risk wrecking your car for that next spot up, because consistent points racing pays too well.