Everyone is different, and I liked the Revenant fights, they were some of the most enjoyable fights in the game for me. I really had to use every trick I had at my disposal to kill them (potions, bombs, spells) and it felt very satisfying when I finally figured out how to win.
I wouldn't want every single fight to as hard as the 3 revenats in the Brecilian forest, but I like when you once in a while find a battle that is extremely difficult to beat, as long as it's an optional fight.
And I think this is the point. They are optional. Compare them to (if you have played it) Kangaxx, Firkraag, and the twisted rune in Baldur's Gate 2. Very hard fights that are put into the game for people who like that sort of thing, but are skipable for a reason. Just like several other hard fights later in Dragon Age, you can avoid them and still continue the main quest without missing out of much.
You can also leave the Revenants for now, and come back later when you are stronger (just like you had to with Firkraag if you got there too early). I can also imagine that Revenants are almost impossible to beat without a healer in your party and plenty of healing potions.
I have almost finished the game now, and so far only one fight in the entire game was extremely difficult to win, and also (as far as I know) unskipable. That was a fight close to the end against a very strong female fighter, and several archers. With hard I mean that I had to reload about 10 times (on hard) before I won.
And are you playing the game on normal? Why don't you change it to easy when you would find the game more enjoyable if you did so? There is no shame in playing on easy (not saying you think so, but some people seem to), the important thing is if you have a good time when you are playing. I had to do the same thing when I played Stalker, and that turned out to be a much better solution than just quitting a game I liked, but was too hard for me on the default difficulty.
