The funny thing is, the extra trades don't help with R14 at all. Everyone's realised that there's no point side swapping players for R14 when they can use the trades to upgrade a dodgy D6/M8/F6 or cover injuries later in the year and get far more overall points out of the trades. The extra trades just end up being a big advantage to those who've upgraded fast and burnt through trades to date. Many would've only been left with 2-3 trades after bye rounds for the rest of the season, but now they will have 4-5 which should be plenty to cover injuries. Those going a bit slower and saving trades, now end up in a position where they could have too many trades for the rest of the season and will get no where near as much out of the extra trades. As someone who was originally saving trades for post byes, I will be hoping for absolute carnage in the second half of the season (this game brings out the worst in me).
I feel like best 14 is going a little too far the other way and bailing out those who haven't planned well for R14. If you only have 14 in R14, you were probably going to struggle to get 18 in the first place. The way I would've gone about it is to take the average number of Rich and WC keepers that teams would've been carrying through R13 (my guess is about 2), and deduct this from the best 18 to get a best... increase the trade limit for R13 and R14 and that's it.
It is what it is I suppose, and I guess it pays to remember that Supercoach aren't in the business of making things as fair as possible for everyone. Their main aim is to keep players interested in the game for as long as possible, as far as that goes, extra trades is the obvious answer.