This may be partly because not everyone has a tattoo, and partly due to the rising popularity of henna and other semi-permanent tattoos. Everyone wants to size you up by asking whether you have braved the needle.
Alert: If you answer this in the positive, this is the can (of worms or beans) opener!
Even if somebody appreciates tattooing as an art, not everybody is born an artist. Though we all wish to be blessed with artistic abilities, this isn't possible every time.
If you didn't catch on the sarcasm, in simple words, it isn't your problem. Live, let live, and moreover, let tattooed people live in peace.