GFCI in kids' room...good idea or not necessary?
What age are the kids?

Most kids have been surviving without GFCI protection for many decades now. But a GFCI has very few disadvantages other than adding a bit of cost.

On the other hand, once you go that far, the question does arise of whether their own room is the only place a problem might arise and whether you might as well invest in protecting the whole house.

In the end, this is a cost/benefit judgement call that only you can make.