The inserts provide pockets for organization---but more importantly, they reinforce the bottom of the bag and give the bag more structure, which helps prevent sagging over time. I can't tell you how many women I see carrying an LV bag that has a sagging base (especially Neverfulls and Speedys).
I carry a lot in my purse so for me, the organizer/shaper was essential. It's my everyday bag and I definitely make it fairly heavy with all of the stuff I have in it. I ordered my shaper from DivideAndConquer on Etsy. The customer service was excellent---I messaged the shop owner about my bag and she recommended the best bag shaper/organizer for the LV Neverfull GM. If you have a different bag, I encourage you to message the shop owner to get the best fit for your bag. One incredible feature of the one I have is that the sides are flexible so that you can still cinch in the sides of your bag for a different look---make sure to ask about this because some of the ones in the shop have flexible sides and others don't.
Here's my Neverfull with no insert in it:
...and here it is, empty, inside of the bag---a perfect fit:
Here is what the Neverfull looks like with the shaper/organizer inside and full of my belongings---you can already see how much more structured it looks.
What I keep inside of my Neverfull:
2 lip glosses/1 lipstick
J.Crew zip pouch to hold receipts, coupons
2 Pairs of sunglasses in cases
Kate Spade wallet
Bobble water bottle
A couple of pens
I highly recommend purchasing a bag shaper/organizer, especially if you have a bag that doesn't have a very strong/structured bottom. It would also be a fantastic option for anyone that has a purse that doesn't have a lot of compartments to it or a bag that's a tote-style. I can't imagine carrying my Neverfull without all of those extra pockets---everything would just get lost and jumbled together at the bottom of the bag.
Do you use a bag shaper/organizer? Let me know in the comments below and thank you for reading!
FTC: I purchased both the bag and bag shaper/organizer with my own money and am not being compensated to write this review.