... also, those stair pieces DO provide additional support for the Step itself...
Moving & carrying HEAVY items up/down the stairs could cause those drawer pieces to sag or break creating more problems.
The kitchen stuff looks good...
... on second thought, those kitchen drawers are NOT doing what I thought they were! Looks like you're losing 1/2 of Right and Left sections basically just making a drawer out of the Center section; making a 45* cut on left & right to get the middle 90*. It's more of a "gimmick"... not giving you much more storage, f any, at all!
Now, if the Left Area had a fixed bottom, at the Drawer Bottom level (of right side drawer), and the Right drawer did NOT have a Left Side, opening access to Left area, that MIGHT be a unique method of being able to use 100% of that normally wasted space. (???) Might be hard to reach some stuff... would have to play with the design... maybe having a curved back of the Fixed Left Area to enable reachability. (??)