Quicken really is the only situation (barring a couple of very specific spell/circumstance scenarios) for which the bonus action casting limitation of 5e is justified. Which is to say, it's actually not justified or worthwhile, as applied to every other spellcaster in the game needlessly, and I'm in favour of it being redacted entirely, as long as quicken retains the restriction, specifically.... and such a revision should not lock out your ability to use reactions on the same turn either (as the current RAW does, and shouldn't).
Generally speaking, however, it should be said that, playing with the BA casting restriction in place... using quicken to cast an additional cantrip is generally a poor use of the meta-magic an a poor use of your sorcery points, in most cases. Rather, the real value in quicken is in freeing up your action for other utility that a sorceress may need; dodge, dash, disengage, hide, stabilising a friend or feeding them a potion, using another item or object in the environment, etc... and still being able to cast a levelled spell at the same time. That is where Quicken's value lies.
