Meh to an extent it actually was since the coat was made to shield from darkness and the one who invented it and those who wear them tend to use said darkness as their form of travel."Travel method" may be a bit misleading since that was never its purpose.
More like the coat had a more broad use than just traveling.
That's likely the case since we only see MX use it once himself.I took the invention of the coat to be more of a pride thing since MX wanted to prove that his attempts at progress were better than the stagnant same old, same old that were the traditions of LoD he had to endure. There really was no purpose in inventing something that's primary function was something MX hated, though I suppose the advantage would be that it more discrete and comfortable.
Whatever his limit is it must be an ungodly high level. So far, of the Xehanorts, only Xemnas has made constant use of it. Though that's likely due to it being an Org stable by that point.As well, I guess even MX is limited and has to acknowledge that he can't be exposed to concentrated darkness for prolonged periods of time. While MX can be said to have come the furthest in mastering darkness, I think a person can only take so much, even MX.
What I have to question though is why the Dark Suit isn't used more often. P:
I'd imagine it's cause Nomura doesn't want to burn our eyes with geezernort in tights. x'D