I've often enjoyed playing games again and again on the highest difficulties to get a real challenge and not just steam-roll over them. Brothers in Arms, Halo, CoD and The Last of Us are all games that I remember being especially fun when played on their highest difficulties. They were far more difficult than easier difficulties (bog-standard infantry able to decimate your health in Halo, taking more than a couple of bullets in a couple seconds being the end of you in CoD, likewise having low health and scarce supplies in TLOU etc) and posed a real challenge as a result. You now really had to consider how you'd arm your character and how you'd deal with enemies - the days of shrugging off bullets were long gone. It could be frustrating but most of the time I enjoyed the authenticity of it, since it felt more realistic to not go Rambo on the enemy.
When it comes to battles in Total War, though, I can't say the same. Even on hard I found them unbalanced and frustrating - comitatenses being outmatched by Germanic levies is just ridiculous - and since switching it down to normal battle difficulty it feels far more realistic. My men no longer get cut to ribbons when they should be able to hold their own in combat, barbarian militias without body armour are no longer a "high threat" to disciplined Roman soldiers protected by chain-mail...it just makes so much more sense and plays so much better.
With all that said, how is it that people are able to enjoy battles on legendary difficulty? Hard felt like the AI got buffed a lot, very hard must be even worse and I can't even imagine what legendary AI buffs are like. How do you guys enjoy it? I can't imagine seeing heavily armoured, disciplined, elite infantry getting run through by levies as being anything other than mind-blowingly annoying and yet it's the case.