Barbie Ex, hands down.

I think this "casuals can't have more incoming damage, too difficult" falls apart the moment you stop thinking that what was done in Abyssos is the only way to do it.
Not to mention that casuals are not stupid. What mainly separates them from highend raiders is that they panic more easily, have a tendency to play reactively and to forget strong cooldowns/ holding them for emergency.

Abyssos increased incoming damage by channelling all the extra damage into massive hits with huge gaps between them.
This caused several problems:
  • it is now more a mitigation check than a heal check because your priority is surviving the initial hit, not healing through it. The gaps are big enough that it doesn't matter how you heal it and how much time you take
  • this in turn pushed the responsibility for surviving them AWAY from healers and on tanks/ dps because a single mitigation was never enough to survive e.g. Ruby Glow, Hemitheos Dark, Light of Life etc.
  • it also enforced bringing a SGE and/ or SCH as both WHM and AST don't have enough mitigation to reliably cover the hits
  • which in turn gave the rest of the party an easy way out by saying "y no gcd shield? :c" for failing the hard requirement
  • hard hits are far more restricting in how you initially deal with them as they require higher HP thresholds in AND stacking mitigation/ shields to survive
  • which in turn also causes them to cause panic from healers more easily
  • gear alleviates the reliance on the rest of the party, removing the sense of danger and turning them into regular, random "moves HP to left" hits - but the long gaps remain, making dealing with them incredibly boring and leaving long downtimes
  • it pushes for a very strict spreadsheet and timetable approach as surviving is the only concern here
  • it has almost no room for error since the hits are designed to kill you; any heal spam will not help you pass a binary mitigation check

What people criticized about the Abyssos approach was disguising "more healing" as hard, binary mitigation checks that enforced a reliance on people who until now had no reason to put Feint, Addle or Heart of Light etc. on their hotbars let alone use it. If the party wiped because they didn't stack enough mitigation (and I want to stress that you needed to stack mitigation, a single Reprisal was not enough), the focus turned on the barrier healer and "y no gcd shields?".

Naturally, many people were displeased with the result of "moar damage". If you implement something poorly than it's not the system itself that is bad, it's the execution.
So interpreting the Abyssos-approach getting a lot of criticism as more incoming damage not being a viable and casual-friendly solution is flawed because it was poorly executed.

Consistent but lower damage has several advantages:
  • it's a true heal check as healing can be used as the only solution to it
  • the responsibility largely remains with healers while tanks and dps can play a supporting role but they are not a hard requirement to solve it
  • it makes all comps equally viable, full stop. WHM/ AST no longer has a signifcant weakness over regen/ barrier or even double barrier
  • consistent but lower damage offers multiple solutions: mitigation, shielding, regen and burst healing. All are equally viable and contribute equally as opposed to creating a "mitigation/ shield > raw healing" divide
  • it is less prone to causing panic as there's no wild HP bar ping-ponging
  • gear makes healing itself easier but keeps the consistent engagement for that part of your role
  • it allows more flexibility for when you use skills and more dynamic gameplay overall
  • it has more room for error because GCD heal spam is a viable solution to make up for mistakes

Increasing damage in all content is viable for both highend raiders and casuals.
But channelling it all into unforgiving mitigation checks isn't.