I still find it strange that people think removing blank lineups would actually change the behavior of managers who simply use the same lineup for every game. It seems to me that if there were no blank lineup option, these managers would still use the same lineup every game, just it would be a set lineup, rather than blank.
But, like I said above, I'm not totally against removing blanks, provided that the substitution pattern choices are improved. Right now, I'd only trust "strictly follow depth chart", and "let coach decide". But those are limited in what players you can get on the floor at any particular time. So, either we get to manually set multiple lineups that have different player groupings, or the 'pick from depth chart' choice needs to work.
To some extent, I wonder if the new GDP changes will start to change the "monotony" of some teams using the same lineups over and over. Depending on how that works in league games (I really wish they had let us test it in private leagues-this is a real shame to only use scrimmages), it's possible that more managers will try changing things up.