In case someone was as curious as I was to how the role bonus interacts with job strength, I made this little calculator that uses simplified dps distributions and custom inputs to play around with different weights for acceptable tax. It's easy to give a ballpark number of how much the role bonus contributes to raid dps but a bit harder to say much that is in percentage of rdps of a single player.
Role tax calculator
With role bonus set to 1% (or maybe a little higher to account for buff multiplication effects) and taxation set to ~90% of role bonus amount results in roughly 5-6% acceptable dps loss to stay within striking distance of the top dps jobs. So if a BLM is doing 100% dps then a ranged should do around 94-95% of that amount. Anything beyond 7-8% loss puts ranged at the risk of being totally replaced. Currently with ranged jobs being ~10% behind the high hitters means that ranged tax is closer to 150-170% of the role bonus amount.
There's an argument that can be made for 100% tax based on the fact that role bonus also gives bonus VIT and therefore HP, so breaking even would still grant an advantage. The tax could also be increased a little bit to account for rdps losses other classes would suffer when doing mechanics more suitable for ranged players, but mechanics like these are very few and far between and honestly quite negligible if it only costs a couple of gcds for the player. Not to mention if those losses can be turned into tank or healer uptime losses they become a lot milder than losses dps roles would suffer. I don't think a tax higher than 105% of role bonus can be justified because we're simply not pressured enough with ranged mobility mechanics.
Over 10% rdps loss for simply being a mobile class is not justifiable. Ranged classes pretty much need a flat 5% buff across the board.