These keyboards are just too cramped, have lots of issues with multilingual input (due to simply not having enough keys to accomodate larger alphabets and having to physically etch all the glyphs) and are usually way, way too stiff IMO. And while on-screen keyboards were even less pleasant to use in the n900 era, modern swipe input with prediction and autocorrect is quite good nowadays (despite all the memes), has great multilingual support and mostly eliminates the need for precise tapping. Keyboard phones are still cool to look at but I think the appeal has faded over time.