For me is is ALL about the sound! work-flo is a bonus. It might help you understand how the “color and Character” can be shaped, this link it is JUST ONE EXAMPLE - one of my favorites the Pultec Pro EQ. A demo of why we like 3rd party plugs - Mix 101: How To Use A Pultec EQ | MixBetterNow.com - YouTube
They can accurately emulate the vacuum tube “character” and “color” of a classic musical sound that we have all heard on hit songs. You do need to have pretty hi-end system and monitors to really hear the improvements.