Since Star Trek: Discovery doesn't take place on the Federation's flagship, like in TOS, roughly 100 years before TOS and in the beginning of a war, it should be logical to assume that the ship's technology would be less advanced and more austere, preferring function over form. However, I see some examples of the opposite:
They have a functioning holodeck, while there doesn't seem to be one in TOS.
The officers on the ship are able to use holograms outside of the holodeck to assist with their everyday duties, like plotting navigation routes, while in TOS and further series it is mostly non-holographic devices.
On the Discovery the bridge viewscreen is quite large and is enhanced with various tooltips.
On the Enterprise it appears to be relatively smaller and just showing a plain non-enhanced view.
I understand that the real-world reason for that is that Discovery series were produced 50 years after TOS and there have been significantly more advanced special effects available at less cost. I'm interested in the in-universe explanation for that. Was that just a stupid fad? Were there some functional reasons?