The absolute removal of flanking and sandwiches would be one of the worst thing you could do to the mode.
Frontlines is not competitive and will never be competitive the same way that casual CC will never be as well. Hoping to get anything competitive with a mode filled with casuals players just interested in having casual fun or doing their dailies is a pipe dream. If you want something competitive in XIV, the current and only mode for it is ranked CC, period. They'd need to add a ranked FL mode for it to ever happen.
Seal Rock is a great map in terms of variety when it comes to its layout where no other map even comes close (Seal Rock has small winding corridors, wide open areas, altitudes, promontories, tunnels beneath those). The main problem with Seal Rock is that the spawns and the nodes are not balanced, and it's a real shame.
I'm not against a 1v1 mode in FLs provided the game gives a lot more catch up mechanics to the losing team in order to make up for it, because 1v1v1 does work where I play most of the time, and most of the time the winning team gets attacked by the two others. People just notice the times one team is being dented and make blanket statements out of it.
Why would it get boring? It's not like AoE would stop being the better option...
Also I can't say I can relate to seeing 16+ players keeling over after executing literally braindead strategies that are even more braindead when 95% of the playerbase is not even playing the same game. Countering it requires so much effort that you'd be better of just fielding your own premade of DRK abusers, much more efficient. If anything getting into the same teams that use this is the most boring shit I've ever had the displeasure to play in FLs. On thing I'll give to modern FL players though, they don't care, they just go back again and again. I do remember days in SB against a different kind of abuse, some teams would just refuse to go back and fight and just wait on their spawn so the game would end.