Firstly, you mention the previous Asymmetric Battles event. I was a player at the time and I don't recall there being bots? I remember playing Top and Bottom Tier multiple times and I honestly cannot recall bots ever having been in the mode. This could be poor memory as it was like a year and a half ago, though.
I have seen it mentioned that the prior Asymmetric Battles was also shut down for a time to do some fixes. I honestly can't recall what they were. So, in that sense, it would seem that this entire event concept is just innately a tough one to pull off. It's unfortunate to recognize that because I think it's really a very fun concept.
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As to your main question, the reality of live server stuff is that things can go wrong. "Games As A Service" is a harsh industry as it's a grueling grind, so we do the best we can to provide a very consistent and good product. That being said, things will slip through and sometimes plans just don't work out.
As to Dockyards and Early Access update events, those are pretty time tested by this point. We've had multiple Dockyards and Many Early Access events, so those are pretty well understood. I don't think there's much to be concerned about over the use of a tried-and-true format. While something unexpected can always pop up, our process is consistent enough that doing something as drastic as disabling a mode shortly after release is notably rare.
I've noted above the Asymmetric Battles seems to be an ambitious project. What looked to be a repeatable format from our previous use of it very quickly slammed face first into a roadblock. Hotfix'ing additional rewards for using Higher Tier ships resulted in no observable change in behavior, so the decision was made to act sooner rather than later. Additional time leaving the mode on would fundamentally damage the community perception of the mode as a PvP experience.
We understand that there are players which enjoyed the mode in a PvE form, but we try to be very deliberate in our design and implementation. That design and implementation did not produce the PvP result we were looking for, so we're currently assessing what needs to happen to be able to achieve that goal. Disabling the mode allows us the most freedom to be able to iterate in the fastest way possible.