Good in theory, but hell if it will ever come into existence in this century. There is too much to render at a time, the netcode requires tons of work to support the buttons, and don't forget the space.
And don't forget that Transwarp is an immediate change from point to destination, and that needs a load time.
"One Sector to Rule Them All" was a much-hoped-for future update, but was recently discussed that Cryptic just can't make that happen yet (especially with the greatly increased loads on their server budget due to needing to run Neverwinter now, as well). Taking it one step further (including all ground and space zones as part of the same map as the sector space maps, making it completely seamless) is an additional order of magnitude or so of difficulty.