I have yet to do this a lot. I think it is because of two things - first, I like playing career so initally I spent a lot of time farming science from the moons... Second, and more important, going interplanetary is way harder than flying around in the Kerbin SOI, but for the wrong reasons. As a couple of people pointed out, the lack of tutorial is most probably the "why", and because of that a new player will likely need to do quite a bit of research on things they initially know next to nothing about on the Internet before they can even attempt it and have a remote chance of success. At least I did. Sure it's rewarding, but it requires that a person is interested in actively looking for the information in the first place.
I remember the first time I tried going to Duna, I built a ship, got it into orbit and tried to set a transfer burn. I had no idea when or where to do the interplanetary burn or how long to wait around before trying to do it or how much deltaV i would need to push into orbit before I should even try that. So I had to find out first. I did succeed, but all the research took time & patience and even with all the necessary information, the interplanetary transfer is pretty hard and time-consuming to accomplish without mods, especially for a new player.
For example, at first I had no idea that nuclear engines are much better for interplanetary transfer than the regular ones. Not sure if this is covered in the tutorials, but I don't think it was at least at that time. I just thought that bigger and more expensive is probably better. I was just wasting time trying to get the biggest thing possible into space in order to satisfy the 5000m/s deltaV requirement that I got from testing maneuver nodes.
The sad truth is that first a new player will need to find out which mods they need to make something like this to happen in a convenient way. I would say at least Kerbal Engineer Redux (to calculate deltaV) and MechJeb (to find out the transfer window). For me, MJ was really the best "tutorial" available for interplanetary transfer, because only after I saw how the autopilot plotted the transfers automatically, I had a rough idea on how/when to actually do it myself.