This is a question I often get when talking to people about handwriting analysis.
How does the personality of a person who always prints differ from the personality of a person who writes in cursive?
Every personality is unique, no one aspect of the writing stands alone.
People who print and prefer to print are preoccupied with the accurate communication of facts unaltered by imagination. They have learned to leave their feelings out of their communication. They generally are not comfortable discussing their personal feelings. It can be difficult to get to know the printer well. Many anonymous notes are printed, often all in caps. Printers like to have control and they can have a difficult time bonding with others. This does not mean that they do not have feelings or don't bond with others just that it is not their strong suit so to speak. They are more comfortable with facts than with feelings. They are highly visual. Many artists print as do technical writer's, accountants, nurses and other professionals whose work requires a high degree of accuracy.
You can see how printing fits in well with technological devices such as smart, phones, tablets, and computers of all types. The stead y increase in printers over they last fee decades may even be a result of these devices. It would make for an interesting research study.