I’ll be honest there is a lot more to be answered about Muehzala Bwonsamdi and Hakkar. How Muelzala convinced helya? What’s the exact relationship between the two loa of death? And why did Hakkar need to be summoned to Azeroth when Ardenweald has portals to send spirits back to the mortal plane??
That's on Blizzard ignoring most of the stuff they write for trolls
Great regeneration? Can be killed by a single arrow
Blessed by the loa of death and the loa of poison? Death by fel poison
Literal millenia of arcane expertise? Written off by everyone as savages
Connection to the natural world and living with the loa? Made fun of their accent at Ardenweald
This world don't give us nothing. It be our lot to suffer... and our duty to fight back.
Helya hated Odyn for turning her into the first Val'kyr against her will, Loken convinced her to turn against Odyn and Mueh'zala convinced she joined the Jailor sometime after she created Helheim (or maybe that's been retconned and Mueh'zala is the one who turned her against Odyn now), it's probably part of some master plan that the Jailor and Mueh'zala created.
Mueh'zala makes a deal with Odyn to give him the power to see into the Shadowlands, Odyn gets inspired by the Kyrian to create his own Val'kyr, turns Helya against her will into the first Val'kyr, Helya turns against Odyn, Mueh'zala brings Helya & Val'kyr loyal to her to the Jailors side, Jailor now has Kyrian-esque servants who can snatch people from their rightful afterlives (which i'm guessing is going to be the reason Sylvanas was taken to the Maw after she killed herself at Icecrown).
As far as Mueh'zala and Bwonsamdi, Bwonsamdi was a mortal priest (presumably a troll priest of Mueh'zala) who Mueh'zala made into a Loa, Trolls turn away from worshipping Mueh'zala because he demanded blood and sacrifices and Bwonsamdi became the Loa of Death for most trolls (except the Sandfury)
Fact (because I say so): TBC > Cata > Legion > ShaLa > MoP > DF > BfA > WoD = WotLK
My pet collection --> http://www.warcraftpets.com/collection/FuxieDK/
I guess the gnome part was just to add some goofyness to the character since Bwonsamdi has some trickster vibes. It also shows that anybody can make a deal with him. Milhouse and Millificent became "iconic" gnome characters so I guess it wasn't that bad. At least, I can understand the reason behind this choice.