Amen to a Yeast Pitch Rate Calc Tool.
And also do the math in the background of Recipe View, using the Batch Size, OG, and ale/lager data to just show how many cells needed. Just show a 3-digit number, in billions? Both WLP and Wye are about 100 billion cells in a package, and most people could eyeball whether they needed a starter. Make it like a 'style' guideline that goes bold when you are out of spec?
Similar to calculating the IBUs from all the various hop drops, times, and gravities during the boil, and it goes bold when it doesn't match guidelines.