Google seems to be listening to the advertiser complaints with AdWords enhanced ads.
Google announced that next month they will be adding a feature to allow advertisers to create mobile bid adjustments on the ad group level. Google said this is to "provide more control and precision over bids in an enhanced campaign."
Google even provided an example of why this is important:
Example: A nationwide retail chain currently uses mobile-only campaigns to optimize bids for several hundred thousand keywords. They’ve found that 95% of their keywords in mobile-only campaigns have bids that are 10% lower than in the equivalent desktop campaigns. The remaining 5% of their keywords have very different bid ratios (ranging from 40% lower to 100% higher) based on differences in performance and competition on mobile and desktop. By using the new ad group bid adjustments for mobile, this retailer can better maintain their desired bids and ROI on different devices as they upgrade to enhanced campaigns.
Seems like some advertisers are excited for this to roll out.
Forum discussion at WebmasterWorld.