Until that happens, you can always enter your tempo as a MM marking and then follow it with System Text. That may actually be more flexible (fonts, etc.) than grouping everything as a tempo indication.
The advantage of treating the elements as a one group would be, that they would be kept together, even if the note spacing changes.
I had exactly this “problem” with combining the MM marking with a text element.
Maybe this function will find its way to a future version.
+1 this would also be advantageous for many film scores where you’d like to show how much a tempo has changed, i.e. after the new metronome marking, in parenthesis (+3) or (-5), etc. Seems like it wouldn’t be too difficult to incorporate a simple prefix/ suffix setting in that lower panel. Better yet, a switch or setting you can turn on or off that automatically calculates your change and puts it in parenthesis right after the metronome marking! Thanks for considering.