That's the feeling I got, Eldar are quite easy to get right. But I suppose the Marine victories are more rewarding... And I do love a challenge 
I think you hit the nail on the head with Marines, from a fluff point of view, they are a very flexible unit but in reality that versatility means nothing when you can only shoot at one target.From a gaming point of view, that "all comers" squad is wasting half of its potential.
Funnily enough I've just created a new list for my second bout at my gaming club. My tactical squad as halved and my scouts have doubled in numbers, i even considered dropping the tactical marines. I can see my tactical squad gathering dust with 7thThus far for me, my Scouts (which I failed to previously mention are 5 man Sniper/Missile units) have given me far better wins than my Tactical Squads have done in my past 10+ games in the month or move I've been playing on a regular basis. That would be why I put the IMHO after the "Tactical Squads are dead". I personally can't see spending points on them any longer while my current set up is working rather well.