Great. Hopefully you mean improving the many cases where fields are not wide enough, where there is extra space (though I appreciate there are probably issues with different monitor resolutions etc). The topic has cropped up many times over the years, with various feature requests. Most of the issues and links in this thread are probably still relevant.
There have been some improvements, but also some backward steps - eg when 'pills' were introduced. Eg in this example, the expression would fill the available field width, but apart from the pill, most of the space is empty:
