This is the flag dialog box:
When you select one of the flag reasons (e.g. "it needs moderator attention"), the dialog then asks you why it needs moderation attention:
- very low quality
- other reason (with a requirement to specify what's wrong)
That is, there are two levels of radio options:
- Select the reason you're flagging the question
- Explain why you're flagging it for that reason
This is marked by the second level of radio options being inset from the first level. Indentation is a common way to denote hierarchy.
The reason for this hierarchy is so we know why you think the post needs moderator attention. Otherwise, we don't know what we're supposed to do with the flag.
The reason you don't see "very low quality" and why you see the odd, two-level-one-radio-button-each UI, is because you're flagging your own post. "Very low quality" doesn't make sense in that context, because if you think your question is very low quality, you shouldn't have asked it. :P
It's unlikely the two-level radio button system would be changed, but it should at least auto-select "Other" when there are no other options.