I think this is why so many online casinos don’t invest in app development (and instead focus on optimizing the site for mobile browsers)… I think they already know that players tend to focus more on the desktop experience than anything else. So paying a big sum for an app seems like a waste of money to them.
To think of it, there is so much process involved in mobile app development and it's maintenance. The casinos already have other costs that comes from maintaining the website and its contents , a mobile app will only increase their cost of operations.
Compared to their websites there will be more people who visit their their website than those who would download the app to play. It is a waste of money.
It makes sense if it is like that, when they want to launch their own application they certainly have to spend money, and even if you look at the benefits which are indeed large they are certainly able to fund it, maybe there is another reason why they do not release their own application.
With me who occasionally gambles at local online casinos they always offer their application on the grounds that gambling is more comfortable, but I myself am more comfortable using it in web form.