Board Thread:The Flash discussions/@comment-9346948-20160518004647/@comment-3423279-20160518061952

Well the Time Wraiths probably weren't thought of then or only attack those who conciously time travel for the wrong reasons, and besides there might be certain events that cannot be altered or else stuff will go really wrong.

If you want an in universe logic here it is, Barry has learned from his experience in getting that Tachyon Device from Eobard that time travel is ridiculously dangerous and might not wish to attempt it unless it is to stop another speedster from messing with it.

For plot based reasons here it is, if Barry went back in time every time something happened he didn't like the story would always go nowhere, he would just go back to his first encounter with Jay and reveal he is from the future and knows he is lying.