the more you have, the trickier it is to set up correctly. you can spend hours dicking around with settings.
more travel = taller and more wobbly.
it’s heavier.
it’s more expensive.
(unless you’ve set it up well) you stand up to sprint up a climb, and all you get is energy sapping squidge-squidge-squidge. eventually you adapt your riding style and stop attacking the climbs.
if you don’t use the travel to help you go faster, and or ride different trails/lines, it can make your rides a little less interesting.
for me it ruined the climb:descend ratio. my hardtail makes the climbs easier+shorter and the descents more interesting+longer. and i think that’s a good thing.
of course, your opinion may differ – i’m an idiot.