How can we get more in depth character customization?

[Rysir]

You mean exactly what XIV does with crafted gear being able to be pentamelded?

Not comparable, 7's materia is vastly superior to 14's as it directly gave spells and abilities so when you chose gear for a massive materia slot list you are giving yourself greater coverage and magical power at the cost of weapon power or physical defense.

14 offers no such thing.