Well, given that internally all the visual events are being turned into XML anyway, it would take a different kind of parser that could parse a construct text grammar and translate back/forth into XML. Add intellisense, color syntax, highlighting and it would be pretty nifty. A text interpreter is not something that would have to be coded from scratch, there are plenty of libraries that could be leveraged. I'm not saying it's a trivial task, but it's doable.
Most of the people I know who come from a coding background and use Construct's main complaint isn't that "they can't do everything with scripting system that they could with coding", it's that (to their eyes), it's that a traditional coding environment makes it easier to trace code flow and keep things organized. And I get that; even with zooming out/etc, an entire screenful of Construct 2 events would probably shrink to a mere paragraph of script text.
It also makes things a little more resilient, copying/cutting/pasting text is a just naturally less prone to potential weird failures that might happen when moving events between event sheets. Having text coding would also potentially make cutting and pasting between Construct projects easier as well, not to mention stock text editor stuff like Find, Find/Replace, etc.
That being said, the keyboard control has come a long way though occasionally you'll lose input focus in the event sheet and have to click on something to bring it back so you can continue using the keyboard.
Even though I'd certainly appreciate the ability to script using code, given the amount of feature-work Scirra has on its to-do list at this time I tend to lean towards making something like this low priority.