Just a quick correction. May seem like semantics, but it's in the spirit of accuracy.
I don't know that it's so that "only a small percentage" of women can orgasm from ANY type of vaginal penetration. I've never seen any data that even suggests it's only a small percentage who can orgasm from intercourse, let alone all types of penetration. What we can say, based on what data is out there, is that a majority of women do not orgasm from intercourse alone.
Remember that there are several different types of vaginal penetration, and that hands and penises are pretty different, cut and uncut penises can even be pretty different, penises, hands and sex toys differ, and among all of those things HOW penetration is being acheived differs.
As well, despite the clitoris not being located in the vaginal canal, some of it, namely the clitoral sponge, or g-spot, does have a side located inside the vaginal canal. So, "can" and "do" when we're talking about these things is an important disctinction. Plenty of women CAN orgasm from various types of vaginal penetration, but for those who do, it is often just a matter of varied play takeing place besides penetration AND a woman finding out what types of penetration, and what ways of doing so, are the thing for her individually.