Before online banking, you needed to download a program on your PC to dial in to the bank. I never used those, and they were all replaced by online banking through the bank's website. But for mobile devices, many companies are moving back to having customers download and install software again. Needless to say, I don't use those either.
Totally. Most apps are really unnecessary as you can have pretty much the same experience on a well-made website. I'm just trying to look through the lens of a casual(non-tech geek) person. This might sound crazy to most of you, but I actually know some people who refused to use certain services just because they don't have an app. Even though they have a decent responsive website. That was the day I realized how seriously platforms should focus on UX.
On a second thought, I don't think Bitcointalk having an app is going to be totally unnecessary. Potential privacy issues aside, having an official Bitcointalk forum app on the Android PlayStore and the Apple AppStore could probably give Bitcointalk a decent boost in traffic.