Akali is an assassin, so if she gets some kills early game and gets fed enough, you can prey for the rest of the game as she will own you all (Except if you stand 5v5, but that's not how Dominion is being played for the moment, team is always separated into at least 2 groups).
I believe problem is that clear strategies and team play aren't yet know by most dominion players (to be understood : We play like crap). She very rarely gets killed because she has a great escape (becoming invisible in her Twilight Shroud) and people don't try to finish her but go for the capture point instead.
Her Twilight Shroud and her dash (ult) are her strongest weapons in dominion. In standard game, when she triggers her invisibility, you just get out of range (unless you are very sure to win, but in this case, she's just trying to escape). Everyone knows fighting Akali in her Twilight Shroud is stupid as she will deal insane damage before returning to stealth without you dealing half as much to her. Except in Dominion, people really want to get that capture point and stay. Other thing is that the to get to your turret is very long (as you fight not between two turrets but at a turret), she has plenty of time to kill you (with her dash) and people also very rarely back.
Conclusion : You stand no chance vs Akali in 1v1 because : either she kills you, either she escapes or waits for teammates in her Twilight Shroud (preventing you from taking capture point). Once she gets enough items (a little more stuff than others), she just goes around dashing to every low life hero. As it is much harder to escape in dominion than in standard game, she basically always makes a kill.
This Meaning you have to have some good team-play to get her, but lets be honest, I've not seen yet some very good team-play in Dominion (too early, people haven't yet defined strategies), except maybe for premade teams.