Simple and useful alterations
Pulling out a seam like that will leave puncture holes and the material will not gladly lay flat. to beat it into submission I first laundered the dress, then before it finished drying, I ironed it. And ironed it. And ironed it. But now it looks and feels great.
I noticed a similar pair of darts on my light blue shirt dress, however, they also gather in a couple of pleats so I will probably leave them alone and just accept that it will be little snug around the waist.
Another issue I have been fighting with on my summer maxi dress is that it is a blouson style dress, that looks terrific when it blouse. Which it does when the elastic hits a cute, little female waist and the material can park itself on top of a hip. Lacking both I have been experimenting with workatrounds. The most promising was pulling up the hanging straps and attaching them to the shoulder straps. The first iteration, safety pinning them to the edge of the shoulder strap far enough up to give the desired amount of blousing worked great, except any time I moved I showed the straps, which looks tacky.Pinning the loose ends of the straps to the rear collar seam worked decently except that it pulled the collar down so I am going to try attaching the straps at the bottom of the armhole. That should work and also allow me to get three lengths pulling the two spots together instead of just one or two. The reinforcement is important because the dress has only been worn a little and already the hanging ribbons are shredding. You can also get ribbon in a rainbow of colors and a full range of widths at almost any good fabric store.