The fact that an activity is interesting is probably an indicator of some value...it's just not a currency that you want to be spending at that particular time. Perhaps, then, the question isn't about abandoning anything but about managing the time you spend on those tasks that have (apparently) inherent interest but aren't contributing to other goals you feel are important.
I say this as a person who has to be very careful not to fall into this trap all the time. I can spend hours messing around with my Vim installation or re-arranging and refining my little personal information wiki or tweaking my blogs...you get the picture.
My solution has been applying, as strictly as possible, calendaring/scheduling and Pomodoro techniques. I intentionally schedule time for that kind of play and I use the Pomodoro technique both while spending that time--so I am as focused as possible--and while I am doing other things (so I feel less temptation to drift off into that fun but lower-value activity).
Depending on the task, I might actually spend my "break" time between work sprints on some of those activities.