I'm glad someone brought this topic up and I have a number of things to say here. First of all I'm disappointed that pits are the source of so many complaints. Pits are a nice feature IMO and I've always been a fan of them not just in jj2, but other games as well. However there seem to be a number of factors present that just ruin the fun factor and add to the frustration of certain players. While playing through most of the AB10 battle levels I've been noting certain keypoints that I feel like should be the subject to some changes.

Bad design and overuse
The first thing I noticed was that pits are way overused in certain levels and in some occasions they're almost forcing you to fall into them. Eg. in ab10btl04.j2l near the center there are a number of hidden ceil springs that push you directly into a pit. If you touch those, theres not much you can do to save yourself. In some cases it's easy to fall down even for misfortunate skilled players (take ab10btl03.j2l as an example). I've found pits to be rather obscured from view, allowing unsuspecting players to easily fall for them. IMO pits should be marked with clearly visible signs, telling players to stay away, but yet allow room to fall down when you're not being careful.

Of course it may all come down to level design, but technically the level designers should consider the balance between the ease of getting roasts and the ease of losing them. It's difficult to get roasts in certain levels as it is even without pits. An ideal level (IMO) would be to let the pits have a minior influence to your score, but shouldn't act as the major factor. Just enough to count against you when some other player beats you to the score limit with those final two/three roasts.

Bugged scoring system
There was one other thing that cought my eye. After a while of playing I noticed that there's something about the scoring system. If you happen to get hit by another player shortly before falling into a pit, the system won't punish your score, but will count as a roast for the attacking player. Likewise, if another player happens to push you into a pit by bumping into you, the system won't add to his score, but will subtract from yours instead.

As a skilled player, I often do things that people wouldn't normally do. Sometimes in a battle I decide to intentionally jump into pits for various reasons. And most of the time some other player that had nothing to do with my decision will get the score.