I completely agree with what you say, but in cases when we follow instructions "from above", we have no choice other than take the screenshots in the format we've been told to... so if it's BMP, it has to be BMP...
In my opinion, if ScreenshotCaptor is capable of managing the BMP format (and it is capable), I would include it in the default format selection. Actually, I would include all formats which SC can handle. Let the user decide which suits their needs best.
In that respect, and as an improvement suggestion, I think the default format selection group box (in Preferences) should change to a drop-down list (instead of the current radio buttons). Additionally, I'd add an "Format options" button (or "Advanced") in which you could set the options for the format (if the format allows any).
anyway, I worked around it by taking PNG screenshots and renaming to BMP (so SC converted them to BMP), but it would have been more productive to take them directly as BMP.
In short, if SC is capable of handling more formats than those allowed in the default image format, then I don't see the point in not letting the user select them.
Of course, this is all said with great respect to you mouser and no intention to impose anything!