There's the rub. You're never going to have 100% of the people with 100% of the information in ANY system. It's pretty much always going to be an informed minority vs an uninformed majority.
Okay. Why does that make it a bad idea to give more value to the votes of the informed? It doesn't matter if it won't be 100%. This isn't an all-or-nothing thing. If the system is changed to increase the number of informed voters, it'll be a change for the better.
If the voting system allowed for a short, simple quiz about the policies of the candidates, and those who pass count for two votes (this is all as a hypothetical example), it would shift the focus of campaigns toward information and not appearance. The candidates would put more effort into making their points simple and educational, rather than bickering about what their opponent did twenty years ago. Those who are truly interested in the election will put forth more effort to be informed, so their vote counts for more and has a greater chance to matter. It would motivate a lot of youth to actually vote in the first place. Seems like a good system to me.