I don't want to install your app
I am getting tired of sites pushing their iPhone app while I am browsing on my iPhone! I’m a minimalist, and I’d prefer to have a small subset of useful apps. Here’s a made up example that is very similar to what I’ve encountered multiple times recently: I’ll search for something simple like “native plants in central texas,” which will lead me to a site like Uncle Jim’s Country Nursery and Feed Store (just an example–this site did not exist at the time of writing); the page load is interrupted by a modal dialog asking me to install their iPhone app. No! I don’t want to install your app! I just want to see if this page has the information I’m seeking (often, it does not).
While tablets and mobile devices will be the primary computer in the near future, I believe the web is the right way forward. There are at least two major mobile platforms (iOS and Android, not to mention Windows, BlackBerry, and any future platforms) requiring dramatically different applications. On the other hand, pursuing a web strategy requires only one app–an app that you need regardless of whether or not you create an app. My advice as a technologist (and my preference as a user) is to pour your efforts into making a solid website.