From my point of view as a relatively new player, the main reasons people seem to think the current edition is the worst ever is price, and nostalgia.

Things are more expensive, which makes the cost of getting new units to keep up with an evolving metagame simply impossible, especially given the speed it's updating in lately. As far as nostalgia, many of the old timers who went over to Warmachine say that 4th Edition - the one they started playing in - was simply much more 'fun and 'balanced,' even though objectively it wasn't. However, that was also when their armies could wipe the opponent from the table, so of course they'd think that was the best era of the game.

Most of the competitively-minded players have moved to WarmaHordes here, thankfully. If they'd just stop harassing other players to get them to join it, I think we'd have a pretty peaceful setup.