Why is winning a bot game worth more XP than losing in PVP?
A big part of what makes lost games feel like such wastes of time is that players hardly get anything out of them. They take longer to queue for, they take longer in champion select, and they take a lot longer to finish, all for relatively much less XP, especially in a loss, which happens roughly half the time.
Meanwhile bot games crank out levels and honors at a higher return rate and with much less downtime between games.
If at the very least PVP games rewarded more XP even on a loss, the time spent would result in more tangible rewards.