I don't understand your question, so, I'm gonna try to make my point clearer.
Let's assume we have a 10 minute 4K project to render.
A decent video stream (AKA standard setting) would be the 50 mbps setting
The best quality would be the 150 mbps setting.
A 3 to 1 ratio.
Consequently, this 10 minute export would result in a 50*60*10:8= 3.75 GB or
150*60*10/8= 11.250 GB file.
Quite a big difference.
Let's now talk about the audio part of the file.
You gave us, users, the ability to change the samplerate. Good.
Depending on the source files, high end users will determine their need, mostly between the 44.1 and 48 kHz settings.
But the second setting we need is the bitrate selection. The same you give us in the video stream settings.
In mp3 or aac, the average bitrate is 128 kbps. The maximum is 320 (in fact 512 concerning aac).
But for complexe or subtile audio, 128 is not enough at all.
By default, without anyway of changing the value, the export remains at 128.
Talking about the same 10 minute project, the audio parts size would be a 9.6 MB stream @ 128 and 24 MB stream @ 320.
As you can size, the filesize concerning the audio is nothingn compared to it video counterpart.
But this small difference could make a huge difference in rendering quality.
So, even if you don't want to add an audiobitrate option, which is a basic option on all video encoders, I think you would please a lot of
your long time supporting customers by setting the audiobitrate to 320 by default or to link it to the desired video quality.
Thanks for reading me.