(The following are entirely personal opinions, they're not intended as a rant against any other styles of art)
I'm 25 now and I've been drawing and painting for as long as I can remember. I definitely had to practice. I think that technical skills are very important, as you have to have a certain level of control and abillity, otherwise it severely limits the work you can do - I'm still not happy with the work I do from a technical point of view, and I'm looking to get better all the time. For me, technical skills are very much a means to an end of creating the image I want to create.
The trouble is, I find it hard not to get proud and over attached to technical skills. Especially when you're young, there tend to be a lot of people around who will be impressed if you can draw/paint things the way they look - friends, family, etc. People tend to be less impressed when you try things that are more "artistic". Ultimately though, there will always be people out there who can draw/paint more realistically than you (such as
John Salt, and that's a painting not a photo). The more photographic you try to make your work look, the more it will look like other people's who are trying to do the same thing. What will really mark your work out as "good" is the artistic expression, your abillity to convey mood through colour/texture/composition/ideas - you just need to make sure you have the technical skill to create what's in your head.
The other problem with spending too much time on "realistic" drawings is that it makes it hard to break out of that style of drawing. I originally got into working in a mixed-media style because I found it easier to be more expressive - if I sit down with just pencil or charcoal, I tend to find myself overworking a picture and getting stuck into trying to draw too realistically. I don't really have a "favourite" medium - right now I just want to get better at making more expressive drawings and paintings, that I can still tie together well with the other elements of my work.