I see what you mean and, normally, I'd agree. However, keeping true to my source material, there are some gameplay devices that will eventually require having separate tilt keys. Also, and more importantly, consolidating the tilt keys into one would decrease the [strike]difficulty[/strike] expertise of movement substantially. What's to stop the player from holding the key continuously?
Things will be much better when controls can be mapped by the user, and even more so when gamepad support is added to Construct. Normally the tilt functions are handled by a controller's shoulder buttons, and keeping them that way is what lead to my current choice of default control scheme. I know very few people use WSAD, but there are far more people who don't have keyboards with numberpads (most laptops), so I can't use LEFT SHIFT and NUMBERPAD 0 and expect my game to run on all platforms.
If it would help you, try changing the left tilt to the F key. Or, should you find a better solution that still allows me to have separate tilt buttons, I will listen with undivided attention.
It's a little difficult to control movement and tilting and barrel rolling all with my left hand at once.
That's because you're not supposed to. The final control scheme uses the G and H keys for weapons and bombs. ideally, you use WSAD and shift with your left hand, and G H and J with your right hand. This is meant to simulate a game controller layout.