Nintendo might be unhappy about that, but I am sure they are more happy about already having 8m subscribers. 25% of the userbase to start with comparing with PS plus at 39% is quite good, considering how much less digital savvy they are.
Nothing happy about having 8m subscribers knowing that the next month it can be drastically reduced.
OP: Seems like many of these subscribers fully aware of Nintendo's crappy service and are only testing it. You know at least when XBL and PS Plus came out let people try it out for free for a brief moment, heck they even had games that gave 1-3 months free of their online service. Nintendo should've given a free trial at least with those that bought Smash Bros.