Hi! Thanks for your kind words.
There won't be any dramatic changes to the population mechanic/interface - it is intentionally about population diversity being a balancing act, and independent role sliders would move away from that in a way that I don't think would resonate with Hive Time's themes or its target audience.
Based on your comment, I'm suspecting that your hive and population are small enough that lifespan fluctuations are playing a large role (smaller populations are higher maintenance and represent one way of chasing increased difficulty for experienced players who want to consciously avoid growth). This becomes increasingly less pronounced as your population moves up above 50 or so. It's also worth keeping in mind that sometimes achieving a particular diversity ratio can require overcompensation in order to arrive there - as in real life, there's a big long gap between saying that a population is equal and it actually getting there. There may be other situations where the best way to achieve a particular population shape is to scale population and infrastructure rather than change balances.
If you just don't like the way that the population mechanic works, you can set the Beesitter slider above 40% and more or less ignore it for the rest of the game.
Hope that helps!