Maybe, just maybe, diving is considered a recreational hobby for some people? Therefore to go diving you don't need to be a *serious diver* [see 'no true Scotsman']. Suunto do pretty well out of their products so plenty of people buy them. I still have a stinger that works fine. So I'm not sure why you 'have an issue with this'. For sure any dive kit sure be recalled straight away when found to have faults in multiple units, but what are you saying - Suunto should have been shut down regardless of this incident as everyone should only be a serious diver and therefore if you're not buying high end expensive makes then you shouldn't be allowed in the water in the first place?
As for manual calculations - the whole of your dive course will be spent on learning manual calculations, creating dive plans and working off manual air cylinder readings. However a dive computer makes life easier especially when ascending, caught in currents or when visibility is poor...."
Way to take things out of context.
I have an issue with people blaming equipment first and themselves second. Dive incidents are almost always down to diver error - and even most equipment failure can be prevented by a few simple visual checks of kit before and after dives.
Also, what I am saying is that relying on wireless kit underwater (which all Suunto integrated computers use) without having an SPG and depth gauge is stupid.
I am also saying that there is never any excuse to run out of gas unless you pop a low pressure hose.
Anyone can count. Any diver should know that at a depth they use X times more gas than at the surface - and if you're in most of the world using the metric system it's dead easy - twice as much @10m, 3x as much at 20m and so on... therefore if they're still down there thinking "hey my gas use is zero and my cylinders are full" (or some part therein) then they are quite simply stupid.
If you know your gas for a particular dive will last, say 60 minutes and your air integrated dive computer or SPG (because you kept that, right rather than rely soley on that little transmitter pod?) half an hour in is not saying you're at 50% or thereabouts then even without adding up you should know something is awry.
But as a diver you know all of that already.