The materia system is not a "crafter only benefits" system. Those materia go into weapons and armor for DoW just as well as into anything DoH/L. Materia is being implemented to replace the repair system as a means to keep crafters relevant. If gear is never destroyed, and getting your own repairs becomes convenient there may not be much of an economy between DoW and DoH/L.
Materia joining is a service you would avail yourself of infrequently. Chocobos are a daily.
Chocobos are transit. They may eventually evolve into more, but even if they do and it's inexorable that everyone's chocobo will be able to fight it shouldn't enable DoL/H to stand on par with DoW unless the chocobo seriously outclasses his DoW owner.
Stealth abilities are necessary when you can't hurt anything. They are being added so that a gatherer can do their job, or so that a crafter can make a delivery without getting killed. If you already have a beefy sword arm you're good to go. Crafters could be just as well served by redistributing the enemy population so that they don't stand near gathering points or in choke points that must be traversed to meet their assigned objectives. With stealth, though, the enemies can remain and the DoW can have something to fight/do. Everyone wins.
Rental chocobos are not the equal of personal chocobos. Only being able to go from a town to some point isn't very useful if you have to visit a lot of camps, which leves are likely to have you do.
DoL/H should *not* be able to participate in every event that a DoW can, not have access to every perk that a DoW can get. I feel, though, that personal transit is not some kind of advanced feature, but a basic one.
Konachibi's links (thank you, by the way) do seem to make it appear that some other way to acquire chocobos is at least being thought about. If it's just a matter of waiting, that's not so bad. It's vague, though, and I'd like to have a clearer picture.