You can have grind for ep and it be successful, you can have grind for resources and it be successful. Where this falls down is in two places, firstly where do you spend the ep and resources? The market has been useless for years. Secondly how engaging is the grind?
Now the first problem is easy to fix, nic sell orders and buy orders of everything on the market is long overdue. With good pricing levels you still leave a lot of room for producers and you at least move the pain from acquisition and provide a market to sell.
The second is a lot more difficult but the basic concept is possible - most successful grinding games take you on a journey doing pretty much the same thing. It seems different because they change the type you fight as your level gets higher. Perpetuum makes a different attempt trying to do the eve method which is more about back story and the beauty of the place you fight in.
Now it's possible to see the journey to level 6 as an effort based ep booster with the whole journey maybe giving you a million ep. There are problems with that of course - ep is transferable over characters and so you could get your ep up to level 6, reprocess your character and rinse repeat for endless ep. Perhaps some sort of character based ep pool from missions would be better.
Once again though is that the real problem is that missions are not engaging enough to be the reason to play. Before the mission nerf(s) when people did squad missions solo then the difficulty level WAS engaging and the payout WAS worth it this just shows that it's within the devs power in a very small time to just fix the difficulty, fix the payouts and sort out the market for perhaps a more engaging game.