How about "I've seen theory X a lot, but I'd LOVE to see it handled a different way! A new take would be fantastic to read!"

Try making it sound more enthusiastic and eager for something outside the standard box. That could help your author be excited to think of a new spin for theory X, rather than potentially being bogged down in "OHNOES they don't like the way everyone writes it! What do I DO?!?!" anxiety.