It's already much better than what we had before .18, but I do support this. I also think spaceplane parts should go with the awesome B9 aerospace pack theme.
Well, planes are a significant part of this game, so real clouds which you could slice through (working concepts were shown back in .18) would be nice. This wouldn't be a big deal should the physics thread of Unity become multithreaded.
Harvester answered this himself: http://forum.kerbalspaceprogram.com/showthread.php/44915-About-the-Tech-tree?p=589661#post589661 http://forum.kerbalspaceprogram.com/showthread.php/44915-About-the-Tech-tree?p=589954#post589954 http://forum.kerbalspaceprogram.com/showthread.php/44915-About-the-Tech-tree?p=591345#post591345 You should go to HarvesteR's profile and look at his posts, lots of interesting info there. EDIT: And another mechjeb-career related one: http://forum.kerbalspaceprogram.com/showthread.php/44915-About-the-Tech-tree?p=591987#post591987