I just want to throw in my opinion here:
A dedicated mobile app makes no sense. Why? It's just a shitload of work for no benefit. There is nothing to gain from it.
To come to your points:
Easier to navigate: If you have problems with navigating the site it's either a personal preference or the site really has a bad navigation. I never had any troubles navigating on the mobile version though. If you are thinking about off canvas navigations or some other type of navigation stuff you mostly see in native apps: these can be done on websites as well, no need to develop a native app for it.
Won't crash as much: Absolutely invalid point. First of all if the site is crashing it's probably a problem with the browser on your smartphone and not with the site itself. LPL doesn't use any fancy features that should blow up your smartphone. Also I've never encountered a problem myself with my old ass iPhone 4 which has problems on a lot of sites. Also developing a native app would probably lead to even more crashes for you since then you have two things you have to maintain: the website and the app, so you need more resources. Also the app has to be a self developed stuff which is most probably not as well engineered as the software LPL uses for the forums (IP.Board) which had years to mature and a company behind it that knows what they are doing.
The only benefit from an app is something like a notification system for new posts on threads you are interested in, or when you get new messages. But as far as I know the same can be achieved by activating mail notifications.
So yeah, a native mobile app is just a shitload of work with nothing to gain.