7th Edition was notorious for "formation creep." Keeping track of multiple overlapping special rules from the core book, the codex, and your specific formation was a chore.
For the collectors and lore enthusiasts, it is a beautiful tribute to the veteran companies. For the competitive players of the time, it was a weapon of mass destruction. For the game designers of today, it serves as a cautionary tale of what happens when elite units are made invincible rather than just resilient.