Right off the bat, I will say that I am not a fan of the upright leash holders, buckets or chairs for the leash to be placed on. I am a fan of having the leash handed to the handler with the loop open for the dog's head. Here's my reasons why I feel this way...
Matt with Sandee/Stewie alluded to safety issues with the "leash pole". He didn't get into what those issues might be, but I know about one big one. Dogs who see their prized toy/reward (leash) just hanging there at the end of their exciting run *do* "target" it, grab the leash and start running around with it - dragging the leash pole after them in a dangerous fashion.
*Yes*, this has happened, on numerous occasions, and it's awful. Should the dog be "allowed" to do this? Nope. But some folks have a hard time training their dog not to do this. Should the handler request the leash be placed on the ground, in a bucket, on a chair or handed to them? Yes. But sometimes we're just human....
Same issue comes up with putting the leash on a chair. How many times have we seen chairs go toppling over when a dog (medium/large) reaches for the leash? I've even seen dogs jump up onto the chair, have it spill over backward and the dog is smacked by the chair. Same as above, is this a training issue? Yes. Some people have problems training it. Should the handler request the leash on the ground, in a bucket or handed to them? Yes, but once again, we're just human.
I understand when some people have said they are concerned about the dog disconnecting at the end of the run. I think it's the handler that will be disconnecting after the run when having to figure out how to; change focus from running the dog to finding where there leash has been put, remove their leash safely/quickly from the leash pole/bucket/chair, untangle their leash, find the loop and then get the dog's head into it. I know I disconnect when I have to do this. My dog is hopping around waiting waiting waiting for me to look at them and praise. (Our leash is not a toy/reward of any kind.) When we're handed our leash correctly, it is so fast, my attention is drawn away for only a second, and we're leashed and happily trotting away being praised. I don't feel like we disconnect at all.
And, of course, there's the time issue. Maybe at some trials time isn't an issue but sometimes time is a big issue to the exhibitors. Let's say it takes 15 seconds from the dog getting the last obstacle to having the leash placed around the neck. This is an absolute possibility, try it.

In fact, as someone who tries Bonuses, it could easily take that for us to run across the ring from wherever our box was, to pick up and untangle our leash and get it over the dog's head. Let's take 250 runs x 15 seconds....and if my math is correct (not always!) that's an extra hour to the day.
It's not logical to expect a dog not to "target" their leash if that's the end of the run reward. After a time or two of seeing where their beloved toy/reward is at the end of a run - on a leash pole, in a bucket, on a chair - any smart dog *will* at least try to get to it - it being a *target* in the true sense of the word....for the dog.

I would guess it'll be kind of hard for judges to have to figure out targeting from non-targeting behaviors....but, that remains to be seen.
The above is all just my opinion from having read the comments from others and my own personal past experience. I just don't want to see dogs dragging the leash pole around or crashing into chairs again, but, I'm afraid we will......

-Kyle