I find it pointless in the sense of the narrative. Why have an action take place if that action is then undone. It would be better to not have that situation at all and instead devote resources to an action that will have a more lasting effect. Rebuilding the Relays makes their destruction pointless since there is no narrative fallout save a time lag in restoring the status quo. A better action to take would have been to destroy Earth but keep the Relays, since you cannot rebuild a planet.
Think of it like this: You see a marching band going down the street. You trip the guy in the front, he falls over, the entire band tumbles all over him, it's a mess. They all get back up, take a minute to sort themselves out, and continue on their way. Can you argue that nothing just happened, just because it sorts itself out to a status quo?
Even if they do eventually rebuild the relays, something was different by not having them for a bit. If they'd had the relays, everyone would have just packed up and shot off home right away. Easy peasey. With the relays down, they can't do that, they're stuck in Sol. Some insist that they're stuck there permanently, I think that's ridiculous, but at the very least, leaving will take time and effort, as well as cooperation. If they go FTL then they need to build migrant fleets capable of multi-year journeys and plot their courses. IF they rebuild the relays that should take at least years and considerable effort.
The results of this should have a monumental effect on the history of the Citadel races, it could bring them closer together if they work together to achieve these goals, it could tear them apart if they aren't able to keep it together and fight amongst themselves for control, all sorts of things could happen, and that's an important story to tell.
If all you care about is the beginning and the end and not the journey then what was the point of the entire series? There were no Reapers attacking people before ME1, and there are none after ME3, so by your definition of a "pointed" narrative,
none of ME mattered at all.