Large areas of solid colour can be problematic over time for certain skins. They may become uneven and blotchy. You won't know until you try whether you are someone with this issue. Shading doesn't show it so much.
Also, one of my tattoos was done with a newly released ink, and now every time I get allergies that ink causes inflammation and I end up with welts where the lines are. Going for large flat areas of ink would be nightmarish if you suffer a similar sensitivity. Ask for an old school, good quality ink, that has stood the test of time and experience over a lot of skins.
You pay for the artist's time. I doubt that flat colouring takes much more or less time than shading, though the skill level is different. You could go to a cheaper artist for lines and flat colour, and get similar results.
Also, one of my tattoos was done with a newly released ink, and now every time I get allergies that ink causes inflammation and I end up with welts where the lines are. Going for large flat areas of ink would be nightmarish if you suffer a similar sensitivity. Ask for an old school, good quality ink, that has stood the test of time and experience over a lot of skins.
You pay for the artist's time. I doubt that flat colouring takes much more or less time than shading, though the skill level is different. You could go to a cheaper artist for lines and flat colour, and get similar results.