This is something that veteran players are going to just have to swallow. The roulette's purpose is to help traffic players trying to queue up to specific instances. The randomness in essence is on what duty a number of players are going for at the time you hit the queue button.

Thats why you have endgame currency tied to it so that it entices players to facilitate that system since everything is super bound to the duty finder in this MMO. Basically, sorry but it is what it is. Either you accept it or find something else to get your tomestones from if it bothers you that much.