I don't think there is much thought put into giving cash as a gift but I have given and received cash as a present. I will only give cash if the recipient has asked or said they are saving up for something as otherwise a present is nicer to receive and more fun to shop for, as for receiving cash it doesn't bother me that much as the people that usually give cash as gifts are terrible at buying presents I like so I would rather have the money, it is always nice to receive a present though.
Yes, in fact I prefer this more. And in our family, this is more preferred to be given. Although personally I would be giving gifts rather than cash. Aunts and uncles give cash because it saves them from the hassle of having to think and to buy the gifts they would give. With giving cash, they wouldn't have to worry whether the gift that they would be giving would be liked or not, because with the cash, they are free to buy anything they like that fits into the cash given to them. Also, those cash given to them as gifts could work as and additional cash for them to add to the money they are saving for something.
I did used to get a lot of cash gifts because I often asked for it and it's also part of our culture to some extent. I ask for cash mostly because I'm not that much interested in material goods anyway and I know my relatives already have a hard enough time thinking of gifts for each member of our family because there's so many of us celebrating during holidays. This is only mostly for big occasions like Christmas though, as I still do get regular gifts on my birthday.