"Uncompressed" means the original resolution of the texture before they compressed it.
Most content is produced in 4096x4096, 2048x2048, 1024x1024 before it's compressed down to suit.
FFXIV splits armourer pieces into "fragments" for certain gear with individual textures for various elements of the gear.
So uncompressed would mean NO loss of fidelity in the texture at the expense of a higher memory cost per texture map. (Diffuse, Normal and Specular Maps) so this can easily eat up a lot of memory, it'll take A LOT of balancing.
It sadly doesn't work like that.
You clearly have no idea what you're talking about. A 64 bit client handles memory virtually no differently than a 32 bit programme.
A 64 bit based programme simply handles more bits at once allowing for a slightly faster and less time consuming computation, but at best this is minimal.
FFXIV currently isn't struggling to process information, therefore a 64 bit client is simply unnecessary for the most part.
It could be done, but it isn't needed and the difference wouldn't be noticed by the vast majority (contrary to what you seem to think)
A 64-bit client would mean virutally nothing for FFXIV:ARR, please do your research on this before making baseless assumptions.
A DX11 Client is an excuse for the team to revisit and also expand their Shader library, particle emissions, lighting and shadow casting and rendering. Along side an array of new features, tweaks and overall performance adjustments that they couldn't do under DX9.
To wave it off as "DX11 will do nothing" is simply not true and frankly ridiculous.
Although some of the features they intend on using were very possible in the DX9 client, the DX11 client is a great place for them to dump the 'High-End PC' content some of the development team themselves have wanted for some time now.
Some of the new features not possible under DX9 are;
Improved asset rendering pipeline
Improved Ambient Occlusion
Improved Transparency Anti-Aliasing (And Alpha Sorting)
Hardware Based Anti-Aliasing
Displacement Shaders
Hardware Based Tesselation
Improved Real Time Space-Based Reflections
Improved Deferred Rendering Support
Direct Compute
Post Processing Effects
Surface Scattering
Hardware Based DoF
And more!
That yet again is a ridiculous assumption that everyone playing FFXIV is running it off a potato.
Considering how frugal the development team are when it comes to balancing quality versus performance as well as attention to detail on top of making sure everything meets a certain standard of quality.
It's very safe to assume that everyone currently running your average DX11 PC will be able to run this client and all it's bells and whistles.