The class roles in the older Battlefield games just made sense. they each had a clear purpose that encouraged teamwork and specialization. Assault lost its identity because, as you said, every class can pretty much do the same thing now. The unique role of being the frontline medic or point-pusher just isn’t there anymore.
And yeah, making Support the medic was such a weird move. It breaks immersion seeing someone with an LMG being the main healer. It doesn’t fit the class fantasy or gameplay logic. Having the original Engineer, Medic, Support, and Recon roles kept everything balanced and distinct: vehicles, healing, ammo, and intel were all covered in a logical way.
It feels like a case of trying to modernize things for flexibility, even though it's the least flexible gadget system in the history of BF.