As I write this, based on notes I started more than a month ago, I know I need to make two points before I start in.
1.) This post is only my opinion and observations of things. That's it. YMMV*.
2.) I haven't been bumped or kicked for the last several milongas (not since the festival). Floorcraft, even on really tight floors like Texas French Bread which was set up even tighter this week, seems to be improving.
On nearly every tango forum, blog and mailing list there are discussions and even very heated arguments about floor craft. Nuevo dancers take a large part of the criticism, partly because they're an easy target. Their dancing is considered "bigger" and their moves are more visible on the floor. But I think the blanket criticism that "nuevo (or open embrace) dancers just dance too big" not only ignores the skilled dancers who manage their space well, tightening up their use of space when the floor is crowded, but also misses what's really creating the problem. I've been kicked and bumped just as often by close embrace couples as open embrace couples. So what did they have in common, if it wasn't the embrace?
Unpredictability seemed to be the biggest factor.
When a group of dancers flow smoothly together around the pista, it's due to a certain amount of predictability. Dancers relax more when they have a better idea what's coming. Conversely, when there is a lot of unpredictability for whatever reason, lots of new dancers, out of town dancers, non-dancers moving in and around the line of dance, dancers take on a more defensive demeanor. Leaders have to constantly watch out for risks to their partner, followers take a little longer settling in and feeling safe, and all of this is going on even before anyone actually gets bumped. Things can eventually settle into sort of a routine, and as the night wears on, people get more relaxed.
There are two habits that seem to contribute most to that state of unpredictability and make dancers feel the need to be more protective. Overtaking and moving in and out of the line of dance (or frequent lane-changing).
I will admit upfront that overtaking is a pet-peeve of mine. A large percentage of the times I've been kicked or collided with, it was because someone didn't have as much room as they thought when overtaking either partner and me, or another couple close to us. But it's also that it creates a bad feeling when it's done constantly. Overtaking, especially on the right side - through the blind spot of the leader in front in the line of dance is rarely necessary. Sometimes a leader has no choice but to overtake the couple in front of him, either for the safety of his partner if the couple in front is dancing dangerously, or because another couple has stopped to do seemingly endless figures on the spot. It happens. However, being annoyed that the line of dance isn't progressing the way you think it ought to, is not a good enough reason to overtake. Someone who constantly overtakes other couples can make an entire floor of dancers feel like they have to constantly be on the look out. Then who can relax?
Overtaking on the right side should be especially avoided. The passing leader may know he has plenty of room, but he's walking into a space the leader before him can't see - or see well. That is, for the leader being overtaken, inherently unpredictable. The follower of the couple in front usually tightens up when she sees or hears the couple behind her leader coming up - which sends a signal to her leader that there's something to watch out for. As I said, sometimes that's unavoidable. When in doubt though, work the space you have.
Dancers that cut in and out of the line of dance (not overtaking couples) - moving into the center and back out again frequently are the other cause of unwelcome "suprises". Lane changing happens - sometimes it's necessary to navigate the floor safely. But you know what people think of drivers that are constantly changing lanes? That's what other dancers think about leaders zigzagging through the line of dance. Lane-changers may not be bumping anyone, but that's likely because everyone is moving away trying to avoid them. I've seen two zigzagging couples put an entire dance floor of couples on edge for two hours. And for the record, both couples were in close embrace.
In my opinion - as all of this has been, the best way to impress your dance partner - learn how to dance in this:
*"Your Mileage May Vary"