Please do not read this as a rant - it is not intended as such. I am greatly satisfied with the game, and I enjoy the challenge of the crafting process as it is. There are, however, a couple things that I think would improve the crafting and merchant aspect of the game.
1. Make all GTNs linked.
I have not seen any official reasons why the GTN is separated. I think it would be an improvement to make ALL the kiosks linked. If I put an item up for sale in the Imperial Fleet, I see no reason why it cannot be available for purchase on Nar Shadaa, the Republic Fleet, or any other place. This stems from the fact that all the transactions are completed through the mail system.
I understand that there might be logistical or programming reasons that the developers chose to keep all the GTNs as separate networks. I can see the potential problem of linked GTNs leading to a complete deluge of results when shopping. However, with the current existing ability to narrow your search parameters, I do not think that problem would be manageable.
2. The ability to remove obsolete schematics.
I would bet my main's complete inventory that I am not the only crafter who finds it frustrating that EVERY schematic EVER learned is there. As an example, once I learn a blue or purple version of a schematic, I no longer feel the need to keep the green version. Even with the current grouping of the lists, the length of the lists is still becoming intimidating.
I will admit it is a very minor complaint, and I would not be offended if it is never changed. It is purely be a convenience issue.
The ability to remove schematics from your existing inventory might very well dovetail with my next suggestion.
3. The ability to "craft" schematics.
As I stated before, this idea might well dovetail with my suggestion about removing obsolete schematics. What if the manner of removing obsolete schematics was to turn it into one of the schematic "items," such as can be found elsewhere in the game. Potentially, I could make a fortune selling a fantastic purple schematic with widely desirable stats on it, such as ones gained through exceptional/critical crafting.
And if it is a schematic that no one would be interested in, I could just sell it to a regular vendor and get a few credits out of it. Either way, it would remove the said schematic from my current list.
I believe that at least some of these changes would be met with the approval of the community at large, and I hope that this post might gain the attention of the developers.