I understand your opinion, but I don't agree. The Horde are still scary, it just detracts from them if they are brainwashed in my opinion.
Hordak already has robot soldiers, and another brainwashed minion in Dragstor. Then there was Adora. I just don't see the need for both Leech and Grizzlor to be essentially tricked into serving the Horde. There was nothing wrong with them just being bloodthirsty and evil villains in the first place who jumped at the chance to dish out more death and destruction in the name of the Horde.
If I read the Leech bio correctly, Hordak made them more powerful with Horde magic and science. Hordak was more than powerful and ruthless enough to command minions without needing to resort to brainwashing.
I know the response to that is then he doesn't have to worry about his minions betraying him, but I would think that an evil being like Hordak would like some ambition amongst his troops. Plus he still has a non-brain washed Catra to deal with. One would begins to wonder why someone as ambitious and prone to treachery as Catra wasn't brainwashed from day one either. I'd worry about her more than Grizzlor.
I'd argue at most he's as intimidating as Skeletor.

However the point about not liking the Horde brainwashing Leech and Grizzlor isn't so much about Hordak's competency as a villain or a leader.
Again, in the mini-comics, Dragstor was brainwashed. I'm fine with that. He was created from a simple peasant and turned into a cybernetic monster. It seems that Leech would be loyal to the Horde because of his own naturally evil disposition and because the motuc bio states that the Horde gave him power similar to what they did with Shadow Weaver. The threat of taking back those magical enhancements should have been sufficient enough to ensure his loyalty, as it does with Shadow Weaver.
In the end it's just comes down to personal preference. I think brainwashing Grizzlor and Leech was unnecessary for their characters and doesn't add to them. Especially if Mattel follows the mini-comic origin for Dragstor (which I hope they do), that will be three key members of the Horde that were brainwashed. It's redundant to me. It also seems idiotic to brainwash the bruiser when you leave you two most ambitious and traitorous minions (Catra and Shadow Weaver) free will to betray you whenever they can. Those would have been the first two I brainwashed. Not Leech and Grizzlor.
