> I must say that it really is totally unintuitive to have put 2 spaces at the end of a line to get a linebreak

Agreed!

One way I get round that is to run text through a Markdown parser first then do a regex to replace \n with <br />

That seems to work fairly will ~99% of the time.

(I do like Markdown though - compared to, for example, BBCode. It degrades fairly gracefully, ignoring the line break issue, so you can just write a chunk of text and it looks good but formatting is fairly easy to pick up and eventually intuitive for more advanced users)