It would be cool to enable personal ARAM "bans" on your own champion pool (like 1 ban per 20 champs you own not counting free this week) that you select in the "collection" tab and you will never roll those champs in ARAM. Your team can still roll them and you can trade for them, but your own personal rolls will never allow it.
"that's what re-rolls are for"
I disagree, I think re-rolls should be best used for changing team comp if you're all AP or something. How many times has the team comp been screwed over because someone re-rolled a champ they didn't know how to play or they kept a champ they didn't know how to play for the team comp? Both feel bad as the team and as the person screwing over the team.