Do y'all use a tent footprint?

Found a good deal on a tent (finally buying my own 1-person tent) and I saw that the footprint is not included. I would have to buy it separately.
I looked up what a footprint is and my questions are:

Are they necessary if it's not raining and if I make sure to check for rocks underneath first?
I normally don't stake down my tent (I don't see the point unless it's windy but I could be wrong about that). What if I just laid down a tarp that I cut into size and place my tent on that?

Just wondering what the general opinion is. I'm looking to keep things somewhat LW, but I'm not obsessed with that.

Thanks guys!