Currently the text widget has a great feature to change the HTML elements (i.e. text=span, paragraph=p, h1=h1, etc.). This gives a lot of flexibility in creating nice interfaces. However, it would be nice to extend this widget with the following features:
<i></i> is generally being abused by front-end developers for icon fonts. Because italic font is easily achieved through CSS, and as far as I know screen readers & search engines don't use it for any particular purposes. They don't change the reading voice for example unlike a lot of other uncommonly used HTML <tag>'s . Also the <i> Tag has the least impact on the HTML page size in bytes, just like <p> <b> <q> etc it is one of few 1 letter tag's defined in the HTML specification. And yeah i for icon...
I wonder which HTML tags should be part of the text widget <i> </i> is valid usage for text. But in case of using an icons font you generally want to leave the text part empty for easier styling between the web font and any other font usage on the page.
Guess there is still HTML tags like <summary> <legend> <blockquote> <cite> that could be added. But quite frankly these don't really add anything big functionally. Except for better structured / index-able websites. But looking at the current DOM generated by Mendix currently isn't really shooting for being the absolute best index-able /SEO optimized low code platform and also with the length and amount of classes added in each element by default the "code cleanliness" doesn't really weigh heavy at the moment either.
The label element in Mendix currently is just for backwards compatibility I believe. But it is an absolutely useless widget in it's current state and it would also be that way if it became part of the text widget. This would only change if you can change the label's "for" attribute, pointing to the HTML element it is the label for. Otherwise you'll always should aim to keep the original "show label" for input option.
Then there is the <hr> element which should definitely not be a part of the Text widget, and should be in itself a separate widget.
Perhaps being able to select different render modes for the container widget, would be nice. For example being able to set it to being a normal .mx-name-container or .mx-name-flex-container and then being able to have a bunch of helper classes to control the flex containers. And also being able to switch it to Tags like: <header>,<footer>,<address> would be cool and help with the readability of the Mendix DOM.
If you look at how webfonts like material design icons and fontawesome can be implemented, most of the time this is by using something like
<i class="material-icons"> cake </i>
Sounds like a good idea! But why do you say <i> for icons? As far as I know, <i> is intended for italics, or for text in an alternate voice.