The alternative would have been redesigning the 737 such that it would be a different plane. There are advantages to keeping it as similar as possible to the previous generation. Boeing was in a bit of a bind. They had a plane (the 737) originally designed for different requirements (the plane is low to the ground) in wide spread use that the airlines wanted them to make more fuel efficient to stay competitive with Airbus’s latest models. If they introduced a new plane that would require the airlines to retrain all their 737 pilots among other things. So Boeing found a way to put new engines on while keeping the plane similar enough as not to make it a new type.

From what I understand, MCAS is a reasonable solution. Where it gets questionable is in not informing the pilots of this new system (but again, there were reasons for that, maybe as it turns out not good reasons), allowing the new system to override the yoke input (Boeing reasoned there was already a procedure for runaway trim pilots would follow), and keying the new system off a single AoA sensor and only having two AoA sensors total so it’s not clear what to do when they disagree.