Lost Ark should completely lean into the no dedicated tank/healer philosophy.
1. Problems to be solved:
1. Not enough supports
2. Support is frankly less engaging than DPS in 90% of content, I say this as someone who mains Paladin at 1480 and has a 1400 Bard on the way up.
3. Support enjoyers:
1. Aren't screwed over in solo content.
2. Don't have to build/buy multiple engraving/tripod sets.
Here is what I would do:
Give every single class access to a new support tab in their character window.
The new support tab has a set of support skills:
1. An activated skill that converts part of your damage to healing.
1. Tripod or engraving system that lets you modify the amount healed, how the healing is applied, and give you meaningful trade offs. Maybe you can pick between 100% heal over time, 50-50 heal over time big bang at start, or 100% big bang after x seconds.
2. Perhaps a range adjustment that increases the range but reduces the amount healed the larger the range you pick, think picking between paladin and bard distances.
3. The length of time the skill is active can be adjusted to suit the class doing the support, which would also adjust the amount of damage converted to healing.
2. An activated skill that gives a shield.
1. Tripod similar to the Paladin/Bard shield tripods/skills that let you pick between things like increased shield, movement speed.
2. Tripod that lets you choose between blocking a debuff or removing a debuff, basically take the paladin and bard philosophies and let you pick.
3. An activated skill that increases attack power/mana regen/attack speed for a period of time.
1. A tripod system that lets you adjust different aspects. Maybe one tripod level lets you pick between attack power given/range/duration. Maybe another lets you pick movement/attack speed versus damage.
4. A skill that prevents x percent of damage on a player for a second, similar to what paladin and bard have now.
1. You get the idea at this point, tripods or something to let you adjust aspects of it. Roll in all the cool parts from paladin and bard and make it so the choices are meaningful.
The point here is to make the choices you make in the support tab meaningful and relevant to content; a good example right now is a Paladin can pick between duration of shield, amount of shield, and purification on their shield.
It also adds another level of depth by letting you pick the class that does support - maybe some fights it's best to have a scrapper do it, others a gunslinger that can stay semi ranged from a boss might be best.
Only a single party member can have the support skills activated, and they would have to nominate themselves so they can't be forced into the role by a popup window or a vote or something when a group is created/joined.
Activating the support skills would reduce your damage to similar levels to Paladin/Bard/Artist right now.
Continue to balance the game around maybe having a support, and leave the battle item system as is.
Congratulations, now there is no reason for there not be support other than DPS don't want to do it.