We hear you. We have a new style coming called “block quote”, which will work like normal body text, but have an indented and altered appearance. We are working on this now.
The current preformatted was intended more for programmer etc, where you don’t want formatting.
The inline style should work in half a paragraph or line, so you could turn it off at the end of a paragraph, and enter a tag there. You could then turn it back on to continue in monospaced font if you want. So you could do what you want, I think, by switching the fixed width style off and on. It works the same way as bold, italic etc.
Hopefully the block style will satisfy you when it arrives. Should be next version all going well.