Not every one of your users is going to be willing to install an app, especially if you don't yet have a high download count and rating. The barrier to entry is much lower with web applications—the user only needs a browser.
Despite not being able to replicate everything that native platform UIs have to offer, you can still implement awesome things in a mobile web UI. Maybe having a good web UI is the first step toward getting those download counts and ratings up for your mobile app.
Ideally, what you should aim for is the following:
- Standard web (laptop/desktop browsers)
- Mobile web (phone/tablet browsers)
- Mobile apps (phone-/tablet-native platform)
Putting an equal amount of effort into all three of these spaces probably doesn't make much sense, as your users probably favor one area over another. Once you know, for example, that there's a really high demand for your mobile app compared to the web versions, that's when you allocate...