Yep, foundation and path building is the most annoying thing for me currently. Lots of times you have to build endless pathways or ginormous levels for your base and it is painful as hell.
Should be, select foundation, click and drag, depending on where you point, it would create a pathway or a rectangular x by y floor. And the same for ramps, walls, stackable conveyor supports (forgot the name of this :) ). Ramps take the cake in obnoxious level.
And you may put this feature as a bonus on some low level upgrade you develop in your base (wassy before space elevator). Or put this already in the beginning.