ARAM - Should Riot give a free RE-ROLL??

There are champions I dont like to play when I am in ARAM like Tryndamere, you need rage to do damage but it's so difficult that ur team let u make a few basic atacks on minions, another kind of champion like this is nunu, or skarner, I just dont like to play this kinda of champs , so I question myself why is the reason u cant re-roll always?, I mean, why u can reroll at least one time in every game of aram to skip a hateable champ with the comp?. Whatever is just now that i tried to play, that i realize that i dont like this map, u cant flank , u cant farm easily with some champs, u play some champs that u are not used to play and maybe that u dont like, the matchmaking is not elo relevant, u cant do too much strategy because u cant freeze lane, u need more comunication to ur team than in the rift and if ur computer is like mine, 4 gb ram , w7, duo core, etc... 20 mb internet without a good graphic card....maybe too much animations of spells and ultis will lag you.

Thank you for u attention, sorry for my bad english. xD