Who here enjoys playing their heart out and anticipating literally everything that could possibly happen and then when a yellow meter shows up on the top-middle of the screen, OH NO! The enemy team throws at you a curveball that you are absolutely not prepared for?
Because I know I do! I totally enjoy being ready for literally everything only to get countered and lose to something that I cannot possibly anticipate.
Overtime is so fun. It’s so psychologically balanced and is totally not a manipulative mechanic that makes your job extremely u fair and unfun.
Oh that Hanzo on the other team has horrible aim and can’t possibly hit one shot? Give him an overtime meter and now he can magically have the mechanics to hit only headshots on squishies 
#ILoveOvertime
It just comes with the territory. Can’t say anything else really.
you know what would be even less fun?
being 1m/10% away from getting the objective, only to lose even though your team needed only 2 more seconds to win.
that doesn’t sound too hot either. with overtime, both teams can do something about the game in the present moment. if it weren’t there, the defending team could just sit in spawn knowing that there’s no way the team could get the point in the next 15s. or attacking teams would give up way too much.
no overtime sounds even less fun. your own team can still do something about overtime, though, so i’d recommend doing just that. 
On capture point maps, if the enemy caps in overtime and you cap with 1:00 or more, you can’t lose and you only need 1/3 of the point.