Nothing is "wrong" with using store juice from concentrate - but you are unlikely to get very good results.
Makers of most store juice, concentrate, and even a lot of commercial fresh presses us predominantly red and golden delicious apples, which are sweet, have high juice yields and taste OK fresh, but dont taste like much when they ferment out.
Its a bit like asking what is "wrong" with using Welshes grape juice concentrate to make wine. Well, nothing really, but dont expect to impress anyone who is used to drinking decent wine.
If you want to make a good cider, start by calling around to the orchards in your area, tell them that you are making hard cider and that you are looking for some good cider apples. Most of them will periodically do pressings for hard cider makers, even though most of what they sell is for mass market fresh consumption. A list of orchards is here:
You can also use google, your local farm bureau, etc. to find good sources. There are still a couple months left in apple season so you have plenty of time
If you live in a place that doesnt have orchards and you have to settle for store juice, then you might want to try a recipe like graff, which is not as dependent on starting with good apples.