It seems there needs to be some meaning to getting Neutral feedback. Im kinda thinking out loud as I type this but what about something like this...
Giving people "infractions" or "marks" to their profile. Think of the infraction as being somewhere between Negative and Neutral feedback. Instead of giving the other user negative feedback, you give them a "mark" on their profile denoting an issue with a previous trade/current trade. Should a person receive 3 infractions, they are placed on "Notice".
Being placed on "Notice" means that the "marked" person would be required to send first regardless of Rep or Feedback score in order to start and complete ANY future trades. Once the "marked" person's cards are received in a promptly order with good communication and condition as described the other person is free to send his/her cards to complete the trade. Once the "marked" user completes 5 successful trades with no further issues from those they traded with, they are taken off "Notice" and their marks are removed.
Now why this over negative feedback?
(New Users) - If Im a new user to trading online (we all were at some point) your already at the bottom of the food chain in regards to getting trades started. You usually have to start with small trades to show your not there to scam them when you want to make an offer for something higher end or worth more. You want your first trades to go smoothly so you can improve your score and move up the ladder. Giving a person like this (or the user in Actinide's BTR) effectively brands them and basically makes them start over in building their rep. Now everyone has their own story about why cards were late or this or that so I cant speak for why Actinide didnt get his half yet but this idea would be an effective warning to him/her that they can't take 2 weeks to send cards unless things were agreed differently.
(Mid Level Users) - These are the people who fall under the " have completed enough trades " area to be able to ask others to send first or send same time. People want cards fast and if your planning on not taking your time to follow the rules and complete the trade in a timely manner, you'll have to start from square one in order to re -establish your credentials if you get too many marks and learn a lesson.
(Trusted Users) - If you've done more than a successful 50 trades, its a good bet you know what your doing. Its pretty much assumed that you know rules and you are the one who usually the people who have no rep or feedback will trust and send first with no issue. There for it falls on you to show how quick and easy trading like this should be and if there is an issue, being able to resolve it without even needing a BTR. Also its a matter of respect between other traders in general that they show the same when dealing with the cards being traded for and away. I sure as hell wouldnt want get 3 "marks" and have my hard earned reputation count for nothing.
Obviously this is a flawed system in some respects but it could hurt to atleast have it out there to discuss and change for the better.
Recently I suggested having BTR Mods was a good idea. Im DEF not suggesting that Sebi and Catinca just relinquish their power to "mod" the BTRs but if there are people like HikingStick or NullParameter who are pretty active on many of the threads, who you guys trust in the Forum as well Deckbox in general, than I dont see an issue with just giving them the power to "Mod" a BTR. Like TyWoo said, the longer a BTR stays unanswered and unresolved, the higher the tempers will rise from those people who are already pissed about something that went wrong in their trade. To run a site like this I know is no easy feat and there are usually alot of other things that that need to be fixed/updated/tested/reset to keep going effectively and when you add in having to listen and sort out people's problems it can be a very daunting task.
there's a link to it on the /r/MagicTCG sidebar