I think your approach might also help people learn what they like themselves - within my family, the answer to "What do you want for your birthday?" is almost always, "I don't know." Will suggest it!
This year, I put a lot of much more varied stuff on both wishlists that I plan on buying for myself, even if I don't get them as Christmas or birthday gifts. IMO, I should have been doing that all along.
My wishlist is on Amazon, but you could keep one anywhere that you like.
This is so much better than any other alternative. The only times I got something I wanted on secret santa was when we used a site to add things we would like to get, and I got the book I asked for. But then... what's the point of the game? Also, Trying to find something that fits the budget and it's not too low, etc... I end up not getting something that I _really_ want,
They all get put under the tree and you unwrap them together.
The surprise is still there because we all suck, more or less, at giving perfect presents even to people we know since years.
So everyone is always a bit surprised about the presents everyone bought for themselves.
You also save an insane amount of money and considerably reduce or actually remove the stress of present-buying before Xmas.
What this leads to, over time, is that you understand much better what everyone likes.
And then, randomly, throughout the year, when you see something that you now understand someone will really like, you buy it and stash it as the bday present for that person.
I.e. only positive outcomes.
The above approach excludes kids of of course -- they still get presents from everyone.