It is a little odd. I'm pretty sure every other MMORPG tries to catch unsubscribe reasons. It's a logical thing to do in order to quickly see why a mass wave of unsubs is happening.

But knowing SE as I do, I don't think they care about actual sub numbers (or other metrics) like other MMORPGs do. If they did they wouldn't say things like "take a break, play other games". They're pretty relaxed overall, and not obsessed with metrics, and they think being obsessed with metrics doesn't lead to a good place (I agree with them on this).

However, it would still be useful to catch feedback from avenues like that.