It is important in most if not all sports that when you are running your feet stay comfortable and supported that's why regular insoles just wont do in sport. hence why sport insoles where created. Specially designed running insoles are meant for people who want to do a lot of physical and use there feet a lot and want to avoid foot pain or discomfort or even damage that could stop a persons sporting career all together. If you just use regular insoles that are flat and do not provide any support such as arch support you may find that you may get problems such as plantar faciitis or even tarsal tunnel syndrome, GOOD REASON WHY YOU SHOULD BUY SOME RUNNING OR SPORTS INSOLES.
Dont let something as stupid as the wrong pair of insoles be the cause of a sporting injury that stops you. They dont even cost that much for a pair of arch supporting orthotic insoles...
The insoles weigh the same as regular ones so its not like you will be weighed down.
You can even use them for day to day use as well.