What Makes Loglines So Hard?

I was lucky enough to have my logline for Across Two Universes included in today's critique session at Miss Snark's First Victim. (Mine's #11, if you'd like to see it.) Earlier today, I happened to read Agent Kristin's comments about what makes a pitch fail. (There are two parts: here and here.) One of the common problems she sees in pitches is problems with the writing.

It occurred to me that perhaps one of the reasons it's so hard to write loglines and pitches has to do with sentence structure. Since you have to cram so much information -- characters, settings, conflicts, goals, and stakes--into just a couple of sentences, there's a tendency to write long, complex sentences. However, this is a different style from what we typically use in our stories.

Would anyone find it useful to review the types of sentences? (e.g., simple, compound, complex, and compound-complex.) I can do a blog post about them if there's interest.