The #1 reason why the chat is so dead:
You guys don't know proper IRC etiquette
First things first. You need a proper client. You can go out and do extensive research but the de-facto standard for most is mIRC:
LinkmIRC is not a free program however it has the same flaw in its trial that WinRAR does (it still works even after the trial expires) and the creators are not going to bother correcting that problem. This means that despite a nag screen at start-up, nothing is stopping you from using it for free.
Other programs include ChatZilla which is a firefox add-on meaning you can leave an IRC chat open in a tab. Another widely used program would be the Opera Browser (built in standard).
Now the reason why mIRC is prefered: The art of IRC is to idle in the channel. Idle means to leave whatever is running your IRC chat open and not interacting with it. You can accomplish this by minimizing your program instead of closing it. This is an extremely old technology that has been perfected over the years, it will not eat your resources.
I cannot begin to stress how important idling is. Take a look at the screenshot:
LinkThis is one channel that has grown over the years. About 90% of that list is currently idle (not interacting with the chat). However, the userbase has grown so much that there is almost guaranteed someone talking. Idling will allow other people to see that other people are taking interest in the chat. Even if you only type hi and seem like the other person is AFK, YOU WILL EVENTUALLY GET A RESPONSE! THIS IS A HIGHLY IMPORTANT CONCEPT AND WHY IDLING IS SO IMPORTANT!
The art of idling will start a slow chain reaction of gaining more users idling at the same time and will increase the amount of activity to expect in great periods of time.
So in short: Don't close that window. Minimize it and idle.