With road bike gearing, being clipped in is important for going up really steep stuff and it's important in a sprint, obviously.

With wider gearing, never had an issue with quality platforms, and never noticed a difference in how much power I can sustain for longer periods, or anything of the sort. Did multiple centuries and 200Ks on platforms without any issues. Offroad I feel more confident being able to put my foot down.

I do 95% of my riding clipped in, though, it's just "right" on a proper road bike. There's no real downside to it on the open road past a bit of a learning curve.