There are people that are taller than six foot and it also depends heavily on whether you have long legs or a long torso.

I am 6'7". I regularly have to ask the person in front not to recline on some layouts. I get aisle/exit row seats if possible, but sometimes it's just not possible. For euro city flights there is no premium economy and the business class seats don't have more legroom either, so there's often very few options for me.

For short flights I will just tuck my legs awkwardly when necessary and have to get up to stretch regularly.