Elder drag is supposed to be a straight up win condition. By the time a team gets it, at minimum, 4 dragons have died and at max, 7.
Lets picture both the max and min scenario.
Scenario 1. 1 Team got 4 straight drakes.
- - - - - - - - - - - - - - Scenario 1.A. The wining team got the elder, in which case they just win harder and end the game as expected.
- - - - - - - - - - - - - - Scenario 1.B. The losing team got elder, in which case they have the chance to bring back the game, assuming they get good fights off and capitalize on the extra kill pressure they have.
In both scenarios, I don't see how it's a bad thing. Either the winning team wins harder and ends the game, or the losing team somehow gets the drag, and therefore has a chance to get back into the game.
Scenario 2. 1 Team got 3 drakes, the other got 4. Honestly, in this case, it's still fine. since 7 drakes have already been killed, one can assume that the game has been going on for quite a while, and both teams are relatively even. At this point, both teams are strong enough that they can stall for days, making the end of the game just a tedious slog of who can play patiently the longest. While baron is strong at this stage in the game, it's honestly doesn't apply enough pressure to result in a win. Elder, on the other hand, forces the end of the game. The team with elder will attempt to force a fight, and which ever team wins said fight, is pretty much guaranteed to be able to end off that 1 fight.
In all of the cases, elder has clear use, and honestly isn't as broken as people like to make it out to be.