It took you long enough, but you are still to be congratulated on having realized it before most.
Unfortunetly, like the rest, you're still stuck thinking it was a mere distraction. Ask yourself, what happened as a result? Who's plan benefited from it? Was it foreseeable?
Harry is still too young, his magic is still weak. He will need some more time before he can be the Hero and Leader Dumbledore and Quirrell wants him to become.
Suppose the rescue plan goes flawlessly. No one would be the wiser, until the time some Bellatrix-sightings or something similar casts doubt on her death. Once her cell is investigated (if enough of her clothes remained to cover her after ten years, the vial would last long enough too), the same thing would have happened, Dumbledore soundig the alarms, and people turning to Harry Potter to save them.
That was the plan, anyways. It succeeded the moment the vial was placed in the cell, so long as they got out without being identified. And it's only a minor inconvenience that it had to happen early.
It's difficult to see only if you think Quirrell lied about wanting Harry as a leader.
That's an interesting idea. However, I think that you may be missing a couple of issues.
For one, if the implication that magically created objects are more susceptible to the Dementors’ aura of destruction is sound, then the vial could easily degrade before the clothes, especially if it was designed to disappear quickly (e.g. hyper-thin glass, or made of something even more fragile than glass).
You do make a good point about the clothes, but honestly, that makes me question why she still had her original clothes at all. When the Dementor was taken to Hogwar...
Update: Discussion has moved on to a new thread.
After 61 chapters of Harry Potter and the Methods of Rationality and 5 discussion threads with over 500 comments each, HPMOR discussion has graduated from the main page and moved into the Less Wrong discussion section (which seems like a more appropriate location). You can post all of your insights, speculation, and, well, discussion about Eliezer Yudkowsky's Harry Potter fanfic here.
Previous threads are available under the harry_potter tag on the main page (or: one, two, three, four, five); this and future threads will be found under the discussion section tag (since there is a separate tag system for the discussion section). See also the author page for (almost) all things HPMOR, and AdeleneDawner's Author's Notes archive for one thing that the author page is missing.
As a reminder, it's useful to indicate at the start of your comment which chapter you are commenting on. Time passes but your comment stays the same.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: