I'm guessing you used a skip potion since all 3 of those HMs had to be completed before you could even accept the quest to kill Leviathan in the level 50 MSQ. It's a non-issue by the time it's required for the level 60 MSQ unless you skip.

It's not a big deal. They're roughly the same if not easier in difficulty than all the other 8 man Normal trials that are also part of the MSQ.

As for why SE didn't build them directly into the level 50 MSQ in the first place, I don't know. Certainly it would have been easy enough to insert the same side quest lore into the MSQ.