I explained why I need multiplayer in a 4x game. It's like a boardgame to me. I want to play it with people. I want to socialize with it. I want it to be the thing that brings my friends/family together for a night of beer and pretzles.
And others have explained why this is not a clear-cut case. You are citing your personal experiences and preferences to make a grand point about what games within this genre are all about and what they need. It is nice and all that you and your friends and families love to play turn-based strategy games like boardgames to socialize with them, but this is not a common pursuit for the majority of costumers. I think the main problem here is that you confuse your approach to be the only sensible one because this is the way you are used to play them. I am just saying that this is not the only way and you are in a minority position.
Why should I bother to play FE:LH? There's no story to speak of, there's no novel mechanics to explore beyond the first 10 minutes.
To use the inherent sandbox tools and the external modding tools to create personalized challenges. Instead of following the RPG story that comes with the box, you are enabled to create your own story every time, instead of relying on the obvious mechanic to play the game, you try a new combination of skills to beat the game.
These games are repetitive by their nature. If you've played one game of Fallen Enchantress to the end, you've seen everything there is. The only reason I have to play them - ever - is to beat up on my friends.
Every game is repetitive by nature, multiplayer can be an option if the gameplay and the demand supports it, but it's not a sure thing. I've played quite a lot of games of Legendary Heroes to the end and still learn new tactics and have fresh experiences, due to the capabilities of map generation, faction/sovereign/unit creation, randomization. Apart from that you completely leave out the area of modding which is a big thing for Legendary Heroes and can pretty much change the nature of the game.
Legendary Heroes follows a developing path of providing players with the tools to create their own interesting experiences, not to follow a given story path or to have quick action bits. Multiplayer can be a sensible option, but it is not a foregone conclusion for 4x turn-based strategy games.