It would be interesting to see the sales figures for Polaris (and Havok) figures of the past, vs how little this combo pack will sell (assuming Marvel doesn't make special efforts to promote it more than they ever did with the Polaris figure).

There are two reasons I see for forcing the figures together with no option of separate buys. One is pretty obvious, the other is conjecture.

Reason #1: forcing more product and visuals of Lorna stuck with Havok. If you want to "collect everything Polaris," they're forcing you to get a pack that pairs her with Havok. Meaning having to spend extra that you otherwise wouldn't, and having to see her associated with him. Of course, the question becomes if people are willing to throw away that extra money, and if Havok included would deter purchase (I'm sure as hell not buying it).

Reason #2: fear for their own nostalgia-baked fandom. If people can buy 90s Lorna by herself, it means they don't have to buy the combo pack. Hype and social media activity (and sales, if they can see the numbers) would reflect that people want Lorna by herself more than Lorna paired with Havok. They don't want proof that people like Lorna as a character in her own right more than Lorna as Havok's girlfriend, so they remove choice from the equation altogether.