As a Beastmaster (BM is popping up a lot here in conversation) here's my spin on this.
For reference, abusing the 0 second cooldown on Beast Tornado is actually not the most effective way of mobbing with Beastmaster, so it hardly comes into play. Fury Strike > Tornado > Fury Strike > Wild Impact > Brutal Strike > x is the better way of mobbing, since Brutal Strike is going to do a ton more damage than a lot of tornados strung together and you stack beast points should you need emergency healing with Cruel Bite.
While it's true both are tanking classes, it's important to understand that they both have different pros and cons. Beastmaster's traits are high health and self-sustain, while Monk is better suited to single-target tanking with a plethora of damage-reducing skills and high dodge.
The real place where these classes differ is in PvP; Beastmaster has the short end of the stick here. while yes, they can stack up tons of health coupled with damage reduction hones/runes and be extremely difficult to take down, they don't exactly do anything back unless you let them hit you for a few years. Beastmaster's damage output in PvP is very very poor, we can't kill healers and we can't beat the other tank classes, so the only killable targets are assassin, rogue, wizard, crecentia and to some extent sorcerer. On the other hand we have Monk, where some of the geared ones in the server are now reaching above 90K HP themselves coupled with their massive defenses and dodge actually makes them tankier than a Beastmaster. Monk, however, can kill people in PvP very easily from full health with Guillotine Fist in a matter of 5 seconds.
Beastmaster is the undisputed PvE champion of the game while being a bottom tier PvP class, and Monk is a mediocre PvE class while being a strong PvP class. It's these distinctions that I think are the reasoning behind Monk not being able to spam Lightning Crush as often as Beast Tornado - because Monk wasn't designed to excel in PvE mobbing. Not hating on Monk or anything here, I just think those are some of the reasons why Lightning Vrush is as it is.
As for the Battle Tactics classes.. I don't think it's fair to compare to them since it's almost unanimously agreed upon that they're very broken right now.