Is there any point to catching rabbits with berries?
Solution 1:
When you use a carrot it is faster. The rabbits will be attracted by the trap immediatly and you can literally stand next to it and wait for the rabbit to go into the trap.
If you do it without carrot, then it takes until the rabbit takes the trap. I have noticed that the amount of time is random though. Sometimes 5 minutes, sometimes I have to wait to the other day till the trap catches anything.
So you have to choose a method depending on your current overall food situation.
As far as I know, Rabbits are not attracted by berries and I'd use them for cooking.
As you noticed, 1 Rabbit does not fill much hunger, that is why I always build a cooking pot as fast as I can. As a stew the rabbits are much more useful, or to feed off pigmen so they follow and fight for you.
Solution 2:
How traps work is pretty simple, if a rabbit gets near it, the rabbit gets caught.
So what you want to do is get the rabbits near the trap and you can use any means to do so.
Using carrot as a bait attracts the rabbits to the trap. I never tried using anything other than carrots so I don't really know if berries work.
BUT I would say there isn't any point to using baits(carrot or berry doesn't matter)
Because as far as I can tell fastest way of catching rabbits is simply putting the traps right on top of the rabbit holes so they will be caught when they get out of the rabbit hole, or if the rabbit was already out of the hole when you put the trap then go near the rabbits and scare them so they run to their holes and get caught in the trap while doing so.