First off, I didn't recommend anything. I posted the link to highlight the potential of our processor, especially in light of what has recently been done with the G2, et al.
Secondly, can you really conclude that the phone will die prematurely if you overclock it? Define prematurely. A processor, running continuously within spec, will function for years without dying (e.g., my overclocked p4 has about 9 years on it, still going strong). Additionally, I think it is safe to say that the turnover for mobile phones is about once every 2-3 years. So probably, by the time the processor would have died given the overclock, the user has already replaced the phone.
Regardless, it is not a matter of how much you overclock - it is a matter of whether you are exceeding the thermal design package (TDP) of the processor. Heat is what damages electronics. If you can keep it within it's TDP, you're fine. Keep in mind that most OC'ing software employs hardware monitoring to ensure that the temp doesn't spike, and if it does, it downclocks.
Finally, it should be noted that companies underclock from the maximum potential of a processor for more than one reason. There is a requirement of uniformity of speed across processors when you are mass producing a unit - due to manufacturing differences, some units can be clocked higher than others, but they are all taken down to the same baseline. Additionally, since this is the mobile world, a premium is placed on battery life. It doesn't take a genius to know that an increased processor speed decreases battery life.
TL;DR: There are compelling reasons to overclock, and do so safely. The reduction in processor life should be irrelevant to the end user.