You got me curious there. Why do you think so? What are the issues you perceive in that department, and how would you fix them?
The trickle of information isn't great. The fact that you are absolutely 100% reliant on your liege for absolutely everything isn't great either; it'd be nice to have an option on automatically sending someone accepting your offer a message with what exactly you want from them. That way, if they join while you're asleep they're less likely to decide there's sod-all to do in the game and immediately give up. I am basing the artificial slowing largely on Tom's statement that the information in the emails isn't on the forum, and the appearance to me that some of it isn't in the manual.
There's also nothing meaningful for landless knights to do. I still haven't heard of any dungeons in the South (and apparently you need multiple knights to do them?), and that means that unless you're actually in a major war there's nothing interesting - except RP, but everyone else gets that too and as such landless knights are still being screwed over.
Nearly all gameplay as far as I can tell revolves around being a lord or greater - so why not add an option to add an estate to the knight offer? Cut out the middleman. That way on entering the game the depth is a bit more visible - assuming it's there, I still haven't seen much sign of it (mostly because my main's liege is busy IRL, but that's not Tom's fault). This isn't artificial, but it does make the game very slow to get into.
Quests were I think meant to alleviate that, but they don't. I haven't seen a single quest offered, having travelled halfway across the map with a side character checking for quests at every settlement. When I asked a more veteran player, they said that it's very rarely used because there isn't actually much to use it for.
If you look a a browser game like Illyriad, it's also set up so you can't win by dedicating your life to it. But it has a very neatly designed set of mechanics so that the time for actions to complete curves upward, and as it reaches the point where the game is too slow to be fun it introduces a new set of quick actions that also scale up in time, and so on. That means that by and large the speed of the game wiggles a bit, but remains at a pleasant level and it only gets slower quite well into the game.
M&F, on the other hand, seems to start slow and stay slow. Instead of newbies being able to occupy themselves with quick but low-reward actions, they have basically nothing to do. It's not necessarily a problem
per se depending on exactly what you want, but it definitely reduces new player retention. That may be a price you're willing to pay, Tom, but it's definitely a price I'm seeing.
The two things I think would make the most difference to the game are just dcumentation and more things for new players to do. The latter, I guess, boils down in large part to promoting confict so there's always a war on, which could be achieved in a number of ways.
M&F is already a zero-sum game in some ways, so just exacerbate that. Make resource densities more extreme - heavy in some places and light in others - and make trading for everything unfeasible somehow. Force realms to fight over resources - which might provoke more intra-corpus fighting as well, as the nobles in the desert start to ask why, exactly, they have to be in the desert and not somewhere better.
This might go over poorly, but give rulers more absolute power - lots of historical wars were fought because the king ordered it done, and the nobles couldn't just refuse (which is what I suspect would happen in M&F as it stands).
Roving brigands have been mentioned before on the forums. Make it worthwhile to have a few knights policing the realm and effectively bounty-hunting. Anything making bandits a more credible threat, really.
This isn't really new player advice, though, so it should probably go in a different thread somewhere.