I think it's possible to be hyper-focused on idle barracks as being a problem. If the reason barracks are idle is that troops were produced faster than they would have been otherwise, then you still have as many troops as you would have had with no increased speed. So it hasn't directly damaged troop production. (Some would argue that it holds you back due to the effects of increasing AW levels on tourney and Spire costs, but so far I haven't noticed that upgrading my AW has resulted in costs I can't handle.)
Whether or not speeding up troop training time is a problem is dependent not only on the training size but also how often you collect troops during the day. On days off or days I work from home (the majority of days), I collect troops every couple of hours or even more often. Thus having a short training time is beneficial because I am training way more troops in those 2 hours than I would have been if my barracks were slower. It is true my barracks is largely idle overnight, but the increase of production during the day from faster barracks far outweighs the "lost" time when my barracks are idle at night.
So it really depends on playstyle. For people who play often throughout the day, the speedier your barracks are, the better.
With that said, I don't have a Needles because I only have space in my city for a GA, which is now level 12.