If we compare them to realm first titles we loose traction in the argument when we get to the fact that there is but one chance at a realm first. Once it has been achieved it's done there is no more competition for it. CMs have run continuously the whole xpac thus giving tons of opportunities to achieve the best times. If that title can be ever changing then logic would allow for the assumption that once it can no longer be competed for it may no longer exist. I can see where people would say the title should remain a permanganate fixture to the last holder but doing that and taking it away entirely both make about the same amount of sense. It really just comes down to which way your perspective on it is facing.
Blizz stops the "season" so they also pack up the roaming title that can go from person to person.
Player ends the "season" with the best rank so they want to take said title home with them.
Think of it like the Xgames where they have the "hot seat". The chair where who ever with the best score sits until someone takes hat seat with a better score, it's usually by the TV commentators. The Xgames winner never takes that actual (comparable to the CM title) seat home with them, they take a gold, silver or bronze medal.
So while letting people keep the titles is what i think they should do, taking stuff away from the game sucks adding it is always better. I can see how they ended up with the conclusion that Blizzard did.