You'll really start to appreciate the difference between knowing design principles and knowing how to use design tools. Tutorials that teach skills or techniques in software will get you about as far as applying a specific technique. Without knowing basic design principles your work is going to look cluttered, samey, not-quite-where-you-want-it-but-you-don't-know-why. I'd also say that jumping straight into UI design is premature for someone beginning a design education. Learning the fundamentals of graphic design is essential, even if at first it seems irrelevant and too print-oriented.
A good design background will help you solve design problems. Right now there's a lot of 'designy' stuff--especially on the web--that's nothing more than the mindless application of a solution to someone else's design problem. There are a lot of missed opportunities to actually communicate, or to make a better tool; all because of groupthink and notions of good taste. Learning about design will help you get out of that rut.