The rewards are an incentive for people to join powerplay but it's an attempt to foster a sense of community for players that pledge for the same power. I've seen in amongst the Mahon players, where they're hauling for the prime minister and not bothered about the reward (Mostly because it's a bit rubbish).Given that all it takes to get access to each Power's toys is three weeks pledged plus 750 merits, that's hardly challenging for a beginner.
The same can be said for engaging with the BGS, exploring, etc. - each player finds purpose in a particular game feature, or not as the case may be.
Players in Solo and Private Groups have access to the same toolset as players in Open - that players in Open can be impeded by other players is, ultimately, their chosen play-style.
I was referring to PowerPlay only for the AI increase. Heck, even an increase in solo/pvt interdiction would get rid of the Bots.Frontier set the challenge posed by NPCs - for all players in all modes. It has been proposed several times that the challenge posed by NPCs be significantly increased (up to the level of challenge posed by PvP players in some cases) - Frontier haven't acted on that proposal and, given the fallout from the bugged weaponry and enhanced AI in 2.1, it would seem that they are not prepared to make the game unplayable for a significant number of players to satisfy the desires of a subset of the playerbase.