We were a little guilty of making the collision box larger than needed for the Xmas tree enemy in Crimbo. Next time we might use collision masks or multiple collision volumes to represent an enemy.
Point 5 - having a highly reactive character - is something we have strived for in our games. We update the player every frame, unlike the enemies which update every other frame. This allows the player's character to feel very responsive to the player's control. Sluggish controls are often found on early 8bit computer games. Normally this is due to taking multiple frames to read the player's input and draw the response on screen. Bad controls let down action titles and highlight the performance weaknesses of the platform.
Developing new games on old machines carries with it a lot of extra work. As well as developing a fun game which will entertain the player, but you also have to overcome the tight limitations of the machine.
We have always aimed to fully push each platform we develop on and to make sure that each game feels that it hasn't been compromised by the machine it runs on.