superior field bosses works like you have write, i have killed them and have tested it myself.
the one with 5 cubes seems to be the regular ones and they are the weak ones; where even a solo player with the current 315 set can solo it without too much difficult and time consuming, so while i do agree that “only” 5 cubes for top dps is too bad, if we look at the bosses strength and even more since we do not have global msg about it, i believe is a safe bet as farming purposes to not allow one group of players to be in the map and call it 20-25 guildes for cubes like before forming a entire “farming” guilds monopolizing every boss since they would offer a lot of profit for everyone involved and now not so much, so it should discourage “high end” guilds of doing it and monopolizing the market-boss at least a little, so now i believe they are meant to be for the ones doing quests-dailies or the luck ones 330 without high end gear that really goes after it , since i myself have killed a few ones when doing quest on my QS at the same level range without problems, this seems to support it, at least a little.
Now that i have write of why i believe this new system in at least in the correct path but with a lot of problems, mainly the supp role seems to be penalized heavy with it and while i do agree that should not be like that, maybe this is imc way of telling us or in this case the players who focus on pure supp roles that is past the time of focusing of only con-hp-defense and use any weapon that you have without trans of anything , because if you have a good weapon even as supp you can kill those bosses, without simple shouting and calling for multiple players to “help” ,of course this is if we take in consideration that you are one of the luck ones that found it, well this goes back to the “auto sufficient builds” that seems to have being talked a lot in recent topics, but i won’t go in deep in it, the text is already long enough.
just to keep it clean, i’m not telling that i’m right in my observation nor that i’m favor of auto sufficient builds and pure supp should go extinct and so on, again the supp role in normal field bosses should be addressed in some way to favor them in some form without doubt maybe simple giving fragments of cube to everyone who do damage, like have being said before could be a nice way to solve it since it would still discourage some “high end” players and guilds of going to monopolize it and let everyone have a share but again this would create new problems
tl:dr i believe this new system of regular bosses seems to be to remove or discourage what always have happen before when higher end level guilds monopolize bosses with their mega high enchant trans character,now it since it does not offer “enough” profit to entice the before mentioned "high end guild " player and the high end guild should now focus on the superior field bosses allowing for the less fortunate players/guilds focus on the regular one and obtain a little profit but the problem of supp role should be addressed in some form.