A while back we were looking at issues surrounding mobile users, our site was built primarily in the late 90s and had lots of caveats and had organically grown beyond anything imagined.

we decided that, instead of an app- we'd rather go with a responsive design, so, we did.

Before: https://web.archive.org/web/20110315032541/http://www.firebo... after: http://www.firebox.com

I can't publish exact numbers, but our turn-over this year as a result (hopefully directly) is much higher- this coincides with our email newsletters that, when used, would open in a standard browser. (we send many emails, most emails appear to be opened on mobile devices)

I think responsive design is far superior to native apps in ecommerce; if only we could scale down the images to make smartphones not need to download 1.5mb of assets for every page :P

You have a point but you are still missing the bigger picture. I'll point out certain arguments that may help you understand my reasoning:

1. if you offer an existing web service for users logins and account management, a native mobile app is probably going to be a much better investment, as it will provide tremendous performance benefits over using the mobile web.

2. If personal data is being collected, it can often be done so more securely in a native app than on a responsive site.

3. You are going to be missing out on the hardware features of the platform like accelerometer on an iPhone.

4. Always a better network connection.

I hope you understand my point of view by now and very frankly in the near future native apps are going to dominate the market even more rapidly.