Gonna have to strongly disagree with you, chief (as well as the other guys who were arguing the same).
I've already argued in a prior post (linked down below, you can examine it for the full argument) why I think using such distinctive pieces such as G2 or HF masks or distinctive armor, or certain weapons pieces would be a disservice to those themes since it would be raiding them for pieces for the sake of supplying G1 for parts. But let me explain why aesthetically it wouldn't work.
From the beginning, the whole argument against CCBS has been centered around a central fear that integrating CCBS or non-Bionicle pieces would result in models that don't feel like they belong in G1. This is a very valid concern. The Mask of Creation, much as the Mask of Control, for example, has G2 runes and language inscribed on it that has no place in G1.
Your argument is that using the Hero helmets would be a fun way to fill out more masks for Agori/Glatorian tribes. To that point, the helmets, at least for the first wave of heroes, attach the same way, and are colored similarly.
But that's really all they have in common with the Agori masks. Closer inspection indicates that there are distinctive differences between the HF first wave masks (differences that are expanded upon in later waves) that would not lend themselves well to representing Agori or Glatorian masks.
The 2009 helmets all have an aesthetic derived from Greco-Roman military or gladiatorial designs, inspired by ancient helmets of ancient Mediterranean or Middle-Eastern origins. Much like the names of the characters themselves (Stronius, Metus, Atakus, Malum, etc) the distinctive pieces themselves are intended to evoke a particular feel, one of a civilization which, despite having once been a civilization of technology well beyond our own, somehow it has reverted to a state of seeming antiquity.
Further investigation reveals similar comparisons. Often, the helmets have extensions or spikes that point backwards. Often the mouth-guard is absent. There is a reason why the designers did not build any sets with Kanohi or helmets from prior years; the wave was meant to be something completely unique.
On the other hand, the HF first wave was likewise attempting to do its own thing. Only twice out of all the heroes and villains released that year were helmets reused from G1--Von Nebula and the Drop Ship, and that was out of simple necessity since they'd already designed so many new molds, as well as the fact those were two masks that were generic enough and broke away from their years' standards that they could pass for helmets in this new world.
But if you look at all the hero masks, you get your own set of common themes--similar mouth guards that can come down or be rotated above the head; antennae on the sides of the head; mechanical, metallic shapes; robotic expressions; aerodynamic vents; and whatever else. Not to mention the helmets are intended to highlight the personalities of the Heroes they're associated with--it's why their appearances reoccur throughout the line.
If you take any of those helmets out of their context and apply them to 2009, it completely upends the feel and environment the designers were going for.
I don't know if you ever watched the designer videos they released when promoting the Toa in G2 (or the G2 artbook for that matter), but on the walls behind them there were many iterations of designs for the respective masks of the Toa--some centered around cyber feels, primitive feels, etc. Each year, they do it again and again, brainstorming exactly what they want each of these helmets to look like. Helmets for Heroes or Toa, especially, get thorough consideration, and every detail on these masks or helmets is a deliberate design choice. I don't know about you, but I strongly recommend seriously considering whether such design clashes are worth sporting in Bionicle.
I could make the same arguments about the other examples you list.
My prior argument on the subject, defending the same argument from a slightly different angle: