Default output to HTML and enable conversion to HTML

[Nostras]

As, quite stated in the title, I'd like calibre to by default convert to HTML and use that as the default output.

The first problem is that outputting as HTML is not possible in the first place.
HTMLZ is, but my device does not support that.
TXT is a bit too bare for my likings.
EPUB works fine, but my device chokes a bit every now and then with larger files. Often run into localization issues if the input file wasn't epub or txt which I can fix with search and replace, but is a pain.
RTF is a wee bit fancier TXT without chapters, naw.
Mobi is something I see no point in using as it's very alike epub.
PDF is awful to use on my device.
The rest of what my device supports is not supported by calibre, the rest calibre offers my device refuses to work with.

According to the manual there is a CLI interface for HTML output, why isn't this an option in the GUI?

Or am I perhaps overlooking something

HTML works best. First time loading takes a while, but flipping pages is as smooth as txt with the markup of epub.

Edit: Well, at least I found out why epub was acting all funky, Calibre casually breaks encoding when adding html to its library. Doesn't help that the conversion HTML -> ZIP casually ignores Common Options. Can't customize plugin either, tutorial wiki doesn't work. Zip -> Epub DOES work and luckily does not ignore the common options. Epub is doable now.