I would definitely make more use of enumerated lists in questions and answers, if the numbers could be controlled. The primary reason I don't use them isn't because I'm breaking them up with text; instead, it's because I break them up with simple whitespace.
One of my pet peeves is text that looks too packed together. There's something elegant about a little bit of whitespace between items in a list, and for this reason, I use bulleted lists.
And while Senshin is right that this is a flaw in Markdown -- and also most WYSIWYG editors that have some form of enumerated list -- the Markdown libraries themselves are open source and extensible. This means Stack Exchange could theoretically solve this problem in the Markdown code and then subsequently publish the changes back into the open source community.
It wouldn't exactly match the spec, which means it would become something like Markdown but not true Markdown. However, if it fixes the problem and allows enumerated lists to be broken up with text and whitespace, then I believe it's a change worth at least investigating.
Lastly, I want to add that adding the backslash may prevent the numbers from automatically changing -- this is the same as what you see people oftentimes do with 1), 2), etc -- the thing to note is that the rendering is not an actual formatted list:
1. Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
2. Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo.
vs.
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo.
As you can see, bulleted list and enumerated list formatting actually indents the text so the numbers/bullet points stand out.