Why aren't there achievements for other mounts that are more difficult to get ?, Blizzard answered this years ago.

Not every mount deserves an achievement, and some mounts will be so hard to get, whether it be by gold or performance, that they don't want to have an unobtained achievement appear in the tab and basically taunt people. Some mounts have a Feat of Strength due to being extremely unique, and that's the sole reason for it.

I've been trying to level my warlock for well over a year now and I've only just hit level 60. There's something very difficult about their playstyle right from the get go. Surely it can't just be me? Is there any chance that the devs can streamline the class. Their resource system is also difficult to maintain as well.

None of those mounts have achievements, but stupid shit mounts like Ice Mammoth has, and no one gives a single F about that one.

Raven Lord has a FoS, but I get the idea.

I tend to post primarily in Recent Forum Posts from the main page.
If I don't reply back to you in a thread, don't get overly offended as it is solely a consequence of my laziness and not out of spite.

Pretty sure after Blizzard released achievement for mechano-hog, they realized they made a mistake about doing achievements for purchasable mounts. Well xcept the double passenger mounts I guess since they are huge gold dumps. List of achievements for each individual mount will be endless if they had one, but there are certain mounts that probably deserve one due to their rarity or difficulty in obtaining but don't have one.

Everyone forgets that a few of these mounts like (Mammoth/Bike/Etc) became achievements in part to that they came out in WotLK and were unique in their design and concept (Passenger Mount/Repair Mounts), and where Achievements were first implemented. Having said that, I do agree some of these mounts deserve achieves or feats, such as the TLPD.