It could be narrative driven in PvE. Ghaul took our light. So in PvE maybe the more story missions we do, the closer we get to regaining our light and full potential. As for PvP. I won't lie, I'm happy Bungie slowed the charge rate down in there. I will hold back judgement on this because it is just the beta and we can't access the full story mode yet. Just my thoughts.