First merge occurs usually 6+ months after its release. After 2.5 years of playing my server got 3rd merge. While first and 2nd merge are usually neccessary, 3rd one pretty much made whole cluster as 1 server, which makes cross server events pointless, as you are fighting within your own server anyway. And those few server events that had z server ranking with relatively few participants = easy to get top place (banner event, wheel of fortune, etc) just got a huge nerf due to merging with another 10+ servers. Unless some of those servers OP is talking about ( I assume it was a merge of 3-4 x 5servers into 1 big server made of those 15-20) were literally dead (which i doubt), only benefit of that merge is konoha world tree lv6 reward and login rewards during first week of merge. I wont refer to new players, as it can be both positive and negative depending on relations, so il just skip this partt.

With such merge they should also consider cluster merge, so spacetime and other activities arent limited to 1 server. However this might be even more drastic change, depending how it's handled.

Ah, and again to OP:

them asking us if we want it 1)wouldnt matter and 2) wouldnt happen anymore. Once they asked this about few features thinking they will get a feedback which supports their intent (cross swb, 13-14runestones) it backfired really hard for them. So they wont ask for it, just implement it anyway, whether we want it or not.