They'd have to break continuity into little tiny pieces to make Soran the villain for this film. Star Trek (2009) occurs mostly during 2258. Assuming that the four years between films is translated real-time, that would mean STID occurs at about 2262.
Now, in fairness, the El-Aurians were a space-faring race long before that, with Guinan having visited Earth in the 1800s. However, the Borg don't attack El-Auria until 2265, 3 years before. Not only would Soran not yet be a refugee, he'd have no motive, or at least nothing that minutely resembled his motive from Generations. He'd be the same villain in name only. It's one thing for Nero's actions to have a measurable effect on someone who grew up in the immediate vicinity of Starfleet so that it could change the course of their life, such as John Harrison, who may or may not be the same Lt. Harrison from TOS. It's another thing for Nero's actions to have an effect on two species who were damn near completely unrelated to the Federation, in an event happening on the other side of the galaxy.
There are other reasons as well. For example, Generations establishes that Soran is over 300 years old, which means if he were in STID, he'd be just shy of 200 years old at the very least, so it's unlikely that they'd cast someone who looks so much younger. (Granted, El-Aurian aging is a bit of an enigma, what with Guinan having hardly aged a day over the course of about 500 years, and she still looks younger than Soran).
I will hijack my own post to say that I always thougt Soran got an undeserved bad rap as a villian. Not only does he have a reasonable motivation and goal (honestly, he's the most believable of all the TNG film villains, and the least generic), but he's Malcolm f***ing McDowell.