So why not just take the extra (for when you just might need it)?
you’re mostly right, but there are things to consider:
# longer travel bikes tend to stand higher ‘pre-sag’ – you might not like that extra BB height (if it is higher)
# you might not be experience the full range of travel behaviour (you might only be using the travel where it’s in it’s ‘linear’ phase, or whatever).
# a longer travel frame needs longer travel forks – they tend to be more expensive and heavier.
like i said, you’re mostly right. but a shitey old mincer like me, given the choice, would take the frame that’s optimised for less travel.