The problem with focusing on "roles", particularly for a game with (I hope) horizontal progression, is that it narrows the definition of versatility. Sure there were technically "tanks" and "support" and "DPS" in RO, but there wasn't a clear role demarcation.
Instead it was more like:
My character is a Flee autoattacker to grind out mobs 1 by 1 without need for potions (avoids cost, restocking time, can carry more weight before needing to go back and sell). My character currently has a Double Hallowed Double Bloody weapon so it can grind Shadow Humanoids super efficiently, but I'd love to grind out a Double Windy Double Clamorous weapon to take on Wind Brutes better.
So in RO each class had multiplicity:
(1) strategy of engaging with the world (both the economy, and combat)
(2) equipment that enabled you to specialise into different niches
In this case my character is fulfilling a less lucrative and lower DPS niche, but the advantage is I don't need to spend on potions and I can low effort grind all day. I have equipment that makes me effective in one niche (Shadow Humanoids) and I am working towards equipment that will make me effective in another niche (Wind Brutes). The opportunities for horizontal progression are vast.
So your wizard can fire wall + bolt, but it can also AoE in groups that mob pull, or spam safety walls for people. And you can go for max damage, or increase your survivability, get more STR for pots because you tend to grind solo a lot, or try to go for instant cast with your equipment/stat spread. Each of these things is a different 'specialisation' of your character that changes how you engage with the world.
Alchemists can go all in on making potion, or into bombs for bossing, or all into aid potion to support, or all in on your homoculous pet. Except for "support" these aren't neatly categorised "roles", but the players still have many completely valid options in how to build their character and to optimise the gameplay of how they like to engage with the game.
Balance in this approach is far more about making the myriad niches that your can tailor your character for somewhat equally rewarding, not the stats on your character or the damage formula. I.e. so there isn't just one supergrind that is so much better than everything else that eveyrone has to do it.
Your autoattacking autostealing rogue isn't going to a DPS leader, or nuke huge groups of mobs, but it fits its niche perfectly. So despite being "weak" and "underpowered" through a modern combat MMO analysis, it's actually perfectly viable, because the game isn't solely about DPS meters on a raid boss with billions of HP.