Long game usually indicated both side of team are trying their best to win the game instead of surrender easily. I suggested to reward the players in both side for their positive attitude by increasing the LP gain of winning team and reduce the LP lose of defeated team. Thanks.
The funny thing is you get less LP per minute the longer the game... Actually it rewards FFing.
It could also mean that the winning team doesn't know how to effectively end games, so an argument for reduced LP also exists.
But LP gains are tied directly to MMR anyway, so you don't want to risk the possibility of people getting into situations where one is 'boosted' by a series of long games rather than actually winning >50% of the time.
Also, Riot is extremely unlikely to do anything that provides incentives to change gameplay patterns. If long games got more LP, players would be disincentivised to end quickly, and instead try to draw out what would otherwise be a stompy match.
