I guess it all depends upon how long the XIN file remains supported in the products. In the short term, being able to specify a text style and honor only those settings as defined in the style would be a start.
But beyond that, when it comes to many of the tools, when you select a named symbology, it locks in many settings. Then it often requires a family of similar named symbologies to allow a commands to "share" those symbologies.
For example, today I was making changes to a sheet with two alignments on it. One change was to add the northing and easting to all of the cardinal point labels. The original labels were set to single line. To add the coordinates, I had to change this to multi-line labels. This effected the justification and the offset. Then, it looked better to annotate one alignment using a Placement setting for the Cardinal Stations of In and the other using Left. The end result was I had started with the original named symbology. To effect my changes, I needed two different symbologies to place these two annotations - in this case, rather than create two new named symbologies, I allowed them to just become unnamed symbologies.
If the ability to assign overrides existed, I would have retained the original named symbologies and simple assigned some overrides for these alternate displays. If I later needed to change the level or font or color, in the case of overrides, I would change the named symbology and be done. In my instance, even with saved preferences, I would have to load a preference, make an edit, save the preference, load a preference, make an edit, save the preference before I would have my XIN updated and this would be on top of making the main edit to the named symbology.
Do I think both of these would make a good CR? Yes. But again, with the progression of Open Roads, I am concerned about the viability of the XIN file. And if it is being phased out, the viability of any CR's with respect to enhancing the XIN file operation is equally doubtful.
You might also refer to this earlier thread that never received any final response or resolution. In my exercise today, I was still seeing this behavior issues.
https://communities.bentley.com/products/road___site_design/f/5922/t/58909.aspx