Whoever told you linings make a garment harder to sew lied to you.
Biggest myth I’ve ever encountered. Linings make sewing curvatures so much easier. Without a lining layer, you’d have to cut little slits into the seam allowance to relieve the tension, but with a lining, the tension is not a problem. Your arm holes will look like perfect TI-84 graphed functions.
If you want a full lining, cut the lining to be 1/2” smaller on all seams so when you turn it over to iron, it’ll pull the outside fabric in a little bit so the lining never shows. A small thing I learned from making ties.
Annie’s dress has a full lining, making it possible to install some chest area padding for us normal folk.