In this week's update we are enhancing the building process with a new system that helps you build more intuitively. This new system allows you to place compound blocks without using the alt key, so you will be able to do only combinations which are more useful.
Thanks to this system, you will be able to use more blocks in survival mode in the future.
https://www.youtube.com/watch?v=0GeMTToj4rM
Full list of new features and fixes: http://forums.keenswh.com/threads/7375485