One thing that puzzles me is why the Italians need a 14000 ton destroyer to put 64 VLS on. Sure, I understand there's sensors, electronics , computer rooms etc, but it looks like less than 10% of the ship's total length. It's about the same length as a tico which has 122 VLS. I do like that they have made space for multiple 76mm guns, but that's not that much space or weight.
Is the weight from creature comforts like carpets, king size beds and 5 star restaurant facilities? (yes, I do know it's not)
I can do some guesses based on what I know about the DDX program.
1) These ships will have major command-and-control facilities, to be able to operate as a lead ship in a naval group.
Italy's major units ( Cavour and Trieste, won't count Garibaldi as she's going to be decommissioned soon ) are also multirole units and won't always be at sea, so the Navy needs more Command-capable units to work with frigates, OPVs, corvettes and destroyers.
Such facilities requires a lot of space.
2) The current displacement is not definitive. RID reported that the Navy is trying to cut the displacement to 13000/13500, but since the project is not completed yet... we can only speculate about the true size of these ships
3) VLS number is unlikely to be 64.
64 was actually a number that some magazines reported before the war in Ukraine, but it was not including the A70 sylver VLS to carry cruise missiles.
I'd say the total number of VLS will be something near 96, but I dont have any confirmation yet.
Anyway, think about a flight 3 Burke.
Such unit has a displacement of around 10k tons.
Now, to a flight 3 Burke, you have to add 3x76mm, command and control facilities ( USN places such facilities on CVNs and CGs ) and probably more.
A Type 055 also is around 13k tons.
So, the new italian destroyers/cruisers are really big ships, but nothing extraordinary...