Well, perhaps not counting them. But I feel like too many people write them off as 'un-important'.
The first thing to remember as a cosplayer though, is that everyone has different tastes when it comes to costumes. We can't force anyone to like our work, despite how great you or others may think it is. And if you are putting yourself out there on the interwebs, you're inviting the world to critique your work. There will be times when people will be much faster to point out the mistakes and discrepancies in costumes than say "hey! Neat job! I love love the accuracy in the details"
That's just people. Sad and unfortunate, but you need to grow a thick skin and prepare yourself for instances like these. Because they are inevitable in the costuming industry.
But, I wanted to talk about "likes".
It's so easy to let the disappointment seep in when you post a picture (or anything for that matter) and check back to find no one has liked it. Then starts the whole cycle in your mind of "why should I bother? no one likes my work". Well, firstly, a costume should be made for you! Not for everyone else. It is definitely a bonus when others are in awe of and appreciate all your hard work. For me, a costume is a recreation of a character or something of the like that I have a connection with and love for. In saying that, motivation to finish said costume is much easier to find when there is more than one party interested in seeing it to completion.
So, when you check back to find x amount of people have liked your picture, even posted a nice comment or two, it's a huge mood lifter. Well, i know it is for me anyway!
You see, I think likes are important because for me, it's a huge motivator. People show interest in my projects and it gives me the motivation to keep at them.
Many cosplayers will tell you they have experienced the motivation slumps when it comes to various projects. People showing their support and offering encouragement has often helped me break out of these moods.
It's not hard to hit the 'like' button when you think someone is doing a good job at something. And seriously, this small act can have a bigger effect than you (the audience) may realise. A small show of support can be more encouraging and more uplifting and motivating than you imagine.
Now, I'm not saying we need to like every single pice of work we happen across. But I think we need to dismiss the idea of 'likes aren't important'. They hold more value than we give them credit for.
I know a lot of people may disagree with this, and continue on the path of "don't count the likes" but this is just my opinion :) and as a cosplayer, I appreciate every single person that encourages me in my work