Indirect interaction, though. Players working for different powers don't ever need to meet. It's specifically made to allow players in every mode to contribute.
Only intrinsic advantages of open for those that crave for direct PvP interaction, or the chance of it, at all times. But, in a game where one of the main selling points was the ability to choose who we play with — which implicitly includes the ability to choose who we
don't play with — I believe you will find that a fair part of the player base doesn't quite enjoy being forced to fight others against their will.
Intentionally so, I might add. The idea seems to be that players are equally valuable, regardless of the mode they are currently playing in.
If five other players are working against you, then it's quite likely they would win, open mode or not.
Also, if, for enjoying a game, you require being able to hunt down and face any other player, then ED might have been the wrong choice from the start; thanks to how its multiplayer works, there will always be large swaths of the player base that are in open mode, influencing the same galaxy, but you won't be able to ever see. More so now that it's been confirmed that those playing the game's upcoming XBox version will share the same galaxy but be unable to direct interact with those playing the PC version.
It's a truly great mechanic that allows those not interested in direct PvP conflict to keep playing, without having PvPers ruining the game for them. All while allowing PvPers to still play and fight among themselves and find the enjoyment they want.
Unless your enjoyment is killed by knowing you will only ever fight those that have chosen to take part in the PvP.
BTW, comparing it with DoTA is like comparing a sardine with a dolphin. They might have some superficial similarities, but underneath they are completely different. Unless you are asking for Frontier to add some kind of evenly matched, instanced, consequences-free Arena PvP mode to ED