Personally, I didn' thave a problem with that warp field. However, I wouldn't call it sentai-influenced. This 'warpfield' thing (basically a psychedelic background thingy, if you ask me) is pretty standard in a lot of Japanese super robot series (Gaigaigar for example comes to mind). I didn't get the impression that Japanese Transformers are so strongly influenced by sentai, rather influenced by super robot series of that time, most noticeably the Yuusha series (design, human-robot interaction, etc)