When you ride with your hands that low, you are not aiding your horse what-so-ever. When you ride with your hands locked down near your horses withers, or stuck on your horses neck between the fences, you are not aiding your horse at all.
Your seat works the back end. Your legs lift the horses ribs up into your seat, and your hands are supposed to be functional, to where they aid your horses front end to lift up and work with what your seat and legs are doing.
When your hands are in the place where you keep them now, you aren't doing this.
Your seat should be functional, to accomodate each ride to each fence. Merge from a full seat, into a 1/2 seat. From a 1/2 seat into a full seat. Your hands must beable to do the same thing. Your hands must beable to give, release, bring back, support, lift, aid your seat and legs in a turn, half halt, hold the outside shoulder, and the list goes on - and they cannot do that, when you have them locked onto your horses body.
Get your hands off of your horse first and foremost. The only time they should be touching your horse, is during your release - no more, no less. At all other times, they should be properly carried and independant, functional aids.
Dressage lessons, will show you this.
Afterall - Jumping is Dressage with Speed Bumps. If GP Jumpers spend 4/5 days a week doing Dressage, I stop and think "Wow, if they do that, there must be a pretty good reason as to why" and if GP horses can do minimally level 3 dressage, then there's a darn good reason behind that as well.
I say, if they education themselves to that level, then you know what - so can I - or darn well try.