I think we need no likes. This page is about photography. If you like a photo someone shares here, you can tell him/her that it's great. If you don't like it, you can tell what do you think to be wrong with it.
And what if a rumor of a camera or a lens gets many dislikes? Will Canon change the specifications? If so, I will give a dislike for all posts about STM and NanoUSM lenses until Canon decides to mark them as EF-V, and returns to ring type USM for all EF(-S) lenses.
Some time ago I've asked for a 300mm IS USM Macro that has a Minimal Focusing Distance about 1 meter. If this post gets many likes, will Canon release this lens sooner?
And if my beetle photos get many dislikes? I surely won't stop taking them, just won't post them here.
The system is based on posts, to give a user praise for useful posts, and conversely, if a post is not useful ... Its not about telling canon to change their products. If you don't like a product, don't buy it, its that simple, and your vote will have more impact on what Canon does than a rating on a forum post.
So, ask yourself, was my post useful to members? They may decide to tell you by voting.
Personally, I don't like the negative aspect, I ban members or remove posts when I think they are inappropriate, not based on the voting. If they are using the rating system inappropriately, then I'll also take action.
The photo gallery also has a rating system built-in, posters have the option to ask for ratings and comments, or turn them off..