Ultimately there will never be any kind of matchmaking system as BGs are completely irrelevant. All these debates about skills/gear are all the same as every other mmo with a pvp system.
Look at WoW. BGs are unranked. No matchmaking. A fresh max lvl60 character can/will be placed in a team against fully geared optimal build characters. Those new people will be decimated 100% of the time. No amount of player skill will match the build up of stats and numbers.
Matchmaking systems exist if there is a reason aka rated pvp content. ESO doesnt have that therefore BGs are largely ignored and mostly useless. If ranked BGs were introduced you would have way more participation in those and a ranking system would be included as well. Until that happens when you hit that button to join the que we get what we get.