Biggest reason: They want to remove high end speeders from the vendors, for economic reasons, and shift that market to the players (via BOE craftable armstech). The credits funnel back into the players (making crafting more worthwhile), and the mats value increases (making gathering more worthwhile).
As a side effect they didn't want to make these speeders craftable for whatever reason. Maybe not worth the effort and maybe because they do think it will be a good idea to let the "founders" only have them.