I've been hearing this argument over and over lately that people complained the Toa Phantoka/Mistika looked nothing like the Toa Nuva even though "no one complained that the Toa Metru looked nothing like the Turaga or that the Toa Inika looked nothing like the Matoran or that even the Toa Nuva looked nothing like the Toa Mata."
And I'd just like to get into why I think that's an incredibly flawed argument. There is a difference to be made between the reintroduction of the Toa Nuva in 2008 and virtually any other transformation we've seen throughout Bionicle's entire run.
When the Toa Mata came out in 2001, we'd barely had a year to get used to how excited we were about them when they were transformed. And when they were transformed, no one complained because we were barely getting into Bionicle as a theme. The Toa Nuva were new territory. Everything was new territory. Yes, their Kanohi were entirely different, but their builds were literally identical to the original sets' and so were their color schemes, so everyone could clearly make the connection based on how little existed of Bionicle at the time.
Then, for a whole another year, it was just the Toa Nuva as the main and only good guys in Bionicle. They even got their own movie which was epic. The Toa Nuva were beginning to set in as the first and foremost faces of Bionicle.
Then 2004 came and we were all (literally) shocked that the Turaga used to be Toa. And when we saw the Toa Metru, they had barely anything to do with the Turaga in terms of design, but that was okay because a) that was entirely new territory and b) the Toa Nuva were at the back of our minds.
Then 2005 came and the Toa Metru which we barely had time to get used to were transformed into the Toa Hordika, which once again no one complained about because a) we didn't get nearly enough time to get emotionally attached to the Toa Metru, visually speaking and b) the Toa Nuva were still at the back of our minds and we were already craving to "go back home" to Mata Nui.
Then 2006 came and the Toa Nuva supposedly returned only within the story and only to get their butts handed to them (even though they're supposed to be the strongest Toa in existence!?), so that left a bit of bitter feeling. We wanted to see the Toa Nuva but only ever read about them. Then the Toa Inika came and they looked absolutely nothing like their former characters but no one complained because a) this was new and (somewhat) exciting territory and b) the Toa Nuva continued to stay at the back of our minds.
2007, Toa Inika to Toa Mahri, barely any similarity between each set. No one complained because a) we were already used to transformations and how they completely changed the appearances of characters and b) at this point we were dying to see the Toa Nuva again instead of just reading about them.
Enter 2008 and neither the Phantoka nor the Mistika looked anything at all like the Toa Nuva. Everyone complained. Is it really that surprising? Bionicle virtually began with these characters and their appearance as the Toa Nuva was the one that had set in the most. For nearly six years we'd thought of the Toa Nuva as their 2002 set forms and/or their 2003 movie forms. This was virtually the only instance of a Toa team existing for so long and taking part of the story without any indication whatsoever about their appearance changing. And then they looked nothing like those six heroes that had been at the back of our minds for six years. Of course that's disappointing. Their reintroduction was (for the first time in Bionicle) supposed to feel like coming home, not exploring new territory for the 100th time. It wouldn't have cost anyone anything if they were to simply make their masks resemble their Nuva forms. That's it. That's the only thing that needed to be done for everyone to be happy. Nobody would've complained if they saw the Hau on a less-than-original Inika build, because the Hau screams home and were dying to come home.
It would've been the first time LEGO transformed a Toa team with the same masks, but it was also the only time that that was genuinely required. And they entirely disregarded that.
And that's my two cents on the matter.