She's completely capable (with her considerable intellect I would imagine rather MORE capable than most, in fact) of making the decision to appear in a cheesecake spread without it being chalked up to invidious social pressures.
Ms. McKellar is hot, she KNOWS she's hot, and she enjoys showing her hotness off -- why on Earth does that bother you? It's not like she's doing this pictorial out of desperation to pay for baby formula or something. She's having fun with what she has, and is raising awareness of her new book promoting the idea that young girls should consider themselves just as capable as young boys when it comes to math.
And I hate to shock you, but even over two decades ago when I was a kid dating was pretty much synonymous with fucking, if you knew what you were doing. NEWSFLASH: People like to fuck! Most of the women I've dated have been willing to have sex on the first date, and they were emotionally-stable, intellectually-fulfilled, financially secure women with solid self-esteem. They just like sex.
A quick GIS for a picture to toss onto this post reveals that she's far hotter than I remember. Good grief!