Because is awesome, you can do basically everything you can dream, you can export your games to every platform (almost) in the market.
When I thought about developing Html5 games, I've chose this language because you can get a lot of market share and your games can be played by a more people than just developing in Java or C++.
Construct2 has an awesome doccumentation and the most awesome forums out there. When you ask you always get a answer.
Thank you all, and I'll be using Construct2 for the next LUDUMDARE.