I don't want VFX (particle effects) in melee. Some sparks and motion wooshies are ok but it needs to look real.
Agree about the feedback importance and that how armor works in D&D (soak all or nothing) complicates things. But the main question is "how much damage did I do?" and it's pretty clear with the floaty number.
Whether the enemy avoids damage because of armor AC, dodge AC, or a magical protection is also feedback. Not as relevant in 5e, but it could be house ruled to be more meaningful. If you see a magical barrier block the damage it's a hint to have your caster throw a Dispel Magic in. BG3 showing that as a dodge gives false feedback.
Impact is what I want to feel in melee, especially with heavily armored characters. Or the lack of impact on a Rogue or Monk.
