This is an extremely popular topic of historical discussion, but it largely revolves around alternate history speculation, which is off-topic in this subreddit. (The question "was it a mistake?" implicitly asks, "what if it hadn't been done?".) Because of that, I doubt you will get a very satisfactory answer for this question here, but you'll probably find a lot of relevant discussion if you search for "Barbarossa" in the /r/HistoryWhatIf and /r/History archives.