As someone who runs a business relying on driving customers via google adwords, I'd say use it.
Right now, google adwords are the best way to get my products in front of people. It works and is worth it. I'd love for that not to be the case. Ads are intrusive. Conversion rates are low but the math still makes sense.
As an aside, my business recently started more aggressively running email campaigns for previous (ecommerce) customers to get them back. We saw a huge return for emailing our customers multiple times in a month rather than once a month.
This is awful, as the conversion rate from email to purchase is something like 0.5%. It's still worth it. All those people are opening email after email. So much wasted time. But in the end, email marketing works and is cheap.
Marketing is one big tragedy of the commons.