People expect a defragger to defragment all files and would suspect a bug if it did not. Also, most people want perfect results and don't care so much about running time.
On the one hand, it is true, but on the other hand, people can start thinking, that MyDefrag simply cannot do such a kind of defragmentation (really quick one) and will prefer Defraggler (for example) as "more powerful" defragmetator, though it is untrue. Many people even don't know, that MyDefrag can use external scripts, which can defragment files a lot of various ways.
I really would like to see "Quick defrag" option among standard MyDefrag options (scripts).
Tip: You might be interested to use the ChunkSize defragment option.
It looks like using this option is even better way to realize this script, because big files still can consist of many small fragments. Thanks.