Reason I want touch screens are that they usually are bigger when chosen... Tired of small rigid displays.
Other reason is that when you use a rigid non touch display, you always need page buttons, cursor buttons etc. To choose what is on the screen, just look at the typical Sequential display navigation system. With a touch display, many of these buttons and softknobs can be replaced with one high quality data encoder, an inc/dec button and enter/exit button. You point at the parameter you want to edit, and it hilights, letting you edit it with the encoder.
On top of tvis, color has been sacked too many times for monochrome displays... Color give clarity and looks better if designed well.
A bigger display also let you group more related parameters on the same pages, greatly enhancing overview and ease of editing, which again let you save buttons on the panel that could be used for more important knob controls, sliders etc. If thought out cleverly, it lets you add more features to an engine without being limited by panel descriptives... Like LFOs for example... You press a button to select what LFO you edit, and a corresponding LED tell you what LFO you are editing, completely restraining you from adding an LFO. later if you wanted to... A big color touch display and clever arrangement would completely change that.
On top, it allow you to easily include XY control pads to the engine.
I would certainly like to see Sequential take on a nrw standard interface like that for coming synths... And on top of that, make an usb or sd card a standard addition to any synth for storing sounds. A simple 2gb sd card would allow any synth to store 128 banks of 128 presets that way... I am amazed we are not even there today with flash being so cheap... Also OS updates would be sysex hazzle free as they could load directly from the flash drive.
If Wavestate had such a display, it would wery certainly be my third synth... It is the most interresting synth after PRO3 for me.
I may get one anyhow, but that depend completely on the MIDI SysEx specifications, because without a full fledged editor, I know this synth would go out the window at some point when i loose my temper over its tiny menu diving display.