There's ~1000 downvotes across ALL regions on Riot threads regarding the removal of dominion...
Out of several million players. So there's a very small percentage of the playerbase who actually care about Dominion, and even less who care enough about it to protest its removal on the forums.
I say good on Riot for finally cutting it loose. Dominion had an outdated map which would have needed a VU, it required champions to be balanced specifically for that map and game mode, and it didn't even have a big enough player base to support a healthy ranked system. Now all of the resources that could have gone into revamping the map can be invested into Seasonal and Event skins for Summoner's Rift and/or Howling Abyss, the resources that could have gone into balancing champions for Dominion can be invested in Champion development, balance and reworks.
In my opinion, Dominion was nothing more than a failed experiment - heck, it never even got enabled on half of the newer servers that have even smaller player bases. I mean, Dominion didn't even have its own micro-mechanic - ARAM has sieging and teamfighting, 3v3 has skirmishing... what did Dominion have? Backdooring? Hiding under towers? It promoted the opposite of healthy gameplay.