DISCLAIMER: sorry for my poor english, hope you can understand this text :)
Firstly: Codeforces is a beautiful platform, sure.
In my mind hacks became useless. Why? Ok, see:
Many easy problems (D1AB/D2ABCD) are "multitest" problems. It is really hard to hack them, because pretests are very strong. But what if I want to hack some hard problems? Hm, i tried to hack some hard problems, but in div2 rooms are very small, and i discovered that there were only 2-3 people who solved some hard problems.
Anyway, i saw that Retired_MiFaFaOvO in one of his screencasts was very annoyed about it too.
But if i will try to hack D2B for example, i would find roughly 10 people, and the chance of succes hack is very small, so it is useless to spend time on it.
So, it is really hard to hack someone, and we can see that the quantity of hacks is very small in some previous rounds!
What is my solution? Ok, lets make rooms bigger from 40 to 80.
What you think about it? Share your opinion in comments.