Sure it won't die, but the pike will certainly do more damage to the knight.
That does not matter if your opponent is losing units but you are not. I am thinking about situations where you can hit the pike with 3+ knights and withdraw. The basic tactic is just to outlast.
Also if you don't have roads and the knight travels from afar, it might not have enough movement points to retreat back far enough to safety from opponent ranged attacks.
Understood, and I completely agree with your thinking. Knights attacking pikes is not because you are desperate, it is because you have little risk of losing them. The roads are a must.
You have to remember that I almost exclusively play multiplayer, so if there's some different conventional wisdom for single player I'm probably not familiar with it.
I will try and keep that in mind, and I have no MP experience. But I cannot image how fights near your cities would be much different.
The Deity AI comes at me with hordes of units, usually a mix of obsolete, current era, and advanced. Those units are a bad mix, used poorly, and have no good promotions.
Your opponent will come at you without a horde, but will still try to outnumber you. His units will be of the current era, just like yours. He gets to pick the time and place, so let’s assume a numerical advantage. He will have a clever mix of units, use them well, and have good promotions.
That said, with the roads pre-built, can we not assume you have several units yourself? I think 3 ranged and 2-3 melee can hold off
any number of equal-era units. Any mounted you throw in are just gravy. I look forward to people telling me why I am being naïve!