I don't know why this is still a debate and a "hot topic." Isn't it obvious that no marketing strategy should be in a silo? You can't put all your eggs in one basket, so to speak… Integrated marketing is the only way.
You need both SEO and PPC and probably a host of other marketing tools as well. We like to focus on the PPC here, but that does not discredit or lessen the importance of all other marketing media!
The benefits of PPC are pretty clear:
1. The results are fast.
2. The fast results provide a great medium for testing. Test your landing page, test your keywords, test your conversion funnel, test, test, test.
3. The data and analytics are measurable, detailed and awesome!