Displaying the plugin UI on the tablet is not a good idea. It would be a good idea if plugins were designed for tablet use, which they are not. As a result, each plugin has a different sized GUI, and may have tiny controls which are not suitable for touch interfaces.
What would be nice and actually relatively easy to implement would be this: Currently, Studio One can remember your MIDI controller assignments, in other words, it remembers for each plugin which MIDI CC is assigned to which parameter of the plugin. If you assigned a specific knob on your MIDI controller to filter cut-off ff in Tai Mai, every time you focus any instance of Tai Mai that knob will invariably control filter cut-off. In other words, Studio One is able to recall parameter assignments automatically as plugin focus changes. This could be extended to the S1 Remote app, so that when a particular plugin is selected, a different customizable interface is displayed on the app. Users would be able to create custom interfaces by dragging and dropping knobs etc. Even if that level of customization isn't possible, a simple grid of knobs, some faders and buttons with editable captions would be better than what we have today.
Here Studio One has an advantage over, say, Lemur, because Studio One is able to determine its own state, whereas Lemur has no clue as to what plugin is currently selected and would require users to manually switch to the correct page or tab, etc.