Alien abductions have been around since at least Sims 2, and in the base game no less.
That was legit the only way you could get aliens at all, and it was only the male Sims that could produce them. You could use cheats, but the legit way was interesting.
In Sims 2, you had to use a telescope, and hope it would happen, males and females got abducted, the only ones that came back pregnant were males.
With Sims 3, you could make Aliens from the get go, but since I never got to play it much, so I don't know how the abductions work.
Sims 4, we got them with Get to Work, and we could make them or get them from abductions. You have to actually avoid the scientist career to not become a target.
I for one live for abductions, and plan to have a Sim enter that career.
Also, as for your point, at the time it was the only way to get aliens (Sims 2), and it has been in a good chunk of the franchise.
