Oh yes, it is completely wrong for one to charge his/her phone overnight. That's totally against the recommended ways phone battery can be charged in order for its maximum strength to be maintained. I am not saying that I have not done it in the time past, but I got discouraged from continuing with it, when the fact on how battery life can be managed hit me. And ever since then, I have strived not to charge my phone overnight.
I know so many people might be wondering what is wrong with charging phone overnight. The reason why is not ideal is that once the phone has gotten to a certain level of charging, which is 80-90%, you're expected to unplug the phone from power supply, because leaving it to attain maximum charged level of 100% would cause the battery strength to wane over time.
For this core reason, charging of phone overnight would affect the battery strength, thereby making it less long lasting as it ought to be if the right charging practices were adhered to.