Why Wee Screens?

This is from a 2009 draft post that was never quite completed.  With a recent Star Wars: The Clone Wars episode, I was pleased to see my idea in action, to wit:

I've been bothered for a long while by the use of tiny screens on handheld devices, most notably in Trek. The amount of data and control options that a tricorder must offer is absurd, especially if communicated via the tiny inch-wide screen. Yet we see the characters providing tons of data and controlling all manner of devices by way of the wee screens and a handful of hardware buttons.

To be sure, this all makes sense from a production standpoint. But in early TNG we see ubiquitous high resolution holography.   We even learn in "The Chase" that the tricorder has a remarkably good holo-emitter capable of projecting a perfectly good representation of a person.   So why not abandon the screen altogether in favor of a holographic screen projection in mid-air?   It isn't like the tricorder doesn't already have a dozen flashing and blinking lights all over it.   And if you're concerned about the person in front of you knowing what you're reading, just have it project a solid block or a black screen on the other side.   If you want to get really fancy, just have it go to the next level and have it only visible for the user, not unlike today's polarization screens that prevent passersby from reading what's on your monitor.

Ironically, it was Star Wars that finally showed the basic technology in action, and seemingly just to show off.   In "The Lawless"[TCW5] from 2013, we see a small comm device which can project the number of signal bars it has above the unit, much like a cell phone would do today with a tiny icon.   This isn't even really a necessary act for the technology, and yet there it was.

I also imagine this technology being useful for phaser targeting.   The smaller phasers don't seem to have any obvious targeting method available, though it is clear they do somehow.   The phaser rifles do have tiny screen things or something going on.   And of course there was the headset for the TR-116 rifle.   Wouldn't it be better to have a little holoprojection screen pop up above the weapon, allowing zoom and better target discrimination?    Then every weapon could be a veritable sniper rifle, which given Data poking fun at the limited range of muskets in an early TNG episode, would make the point make more sense.