Still people here are in the mistaken belief that lost of 'options' exist for tall passengers, and it just is not true.
For instance, buying an adjacent seat in some airlines is a completely pointless exercise, as the seats are fitted with non movable arm rests, so a leg cannot be stretched over to the adjacent seat even if this is empty. Even if there are movable armrests, they must be down for takeoff/landing - so again an impossibility. I have actually been on an aircraft where I had my leg out to the side, and my knee was in front of the seat back in front - a crazy situation.
In the case of aisle seats, I would suggest YOU try sticking your legs out into the aisle on a flight. Firstly, you will get passengers passing by banging you and also tripping on your feet. The tripping happens much more often than is easy to believe- never understood why. You will also get cabin crew wheeling trolleys into your knee (I have experienced this many many times with no apology or excuse me). Finally, similarly to above. an aisle seat is next to useless in this respect if it has fixed rigid arm rests, as is seen on Easy jet aircraft, and a lot of charters.
For the average punter, business class is just way too expensive (and extravagant) and premiumn economy on some airlines is also too expensive, as it includes lots of unnecessary extras.
Like I said before, I do not mind having to pay more for extra legroom, but why can't I have it without all the fancy extras etc.. which unnecessarily add to the cost.
And for the record, for those people who suggest booking an adjacent seat - just try doing it for your next holiday with lizzie drip serving you in the travel agents. It is a process akin to pulling teeth.
The real truth is that some of these 'options' for tall people are invariably not available or are impossible due to the type of seating.
It is easy to be glib about this, if you are not tall, but the reality is actually a bit of a nightmare.
Incidentally, legroom needs for a given passenger are not only related to the persons height, as some regular height people can have very long femurs (thigh bones). You do not have to be extremely tall in height to suffer in this respect. This is in fact the case with myself. My femurs are very long for someone of 6'2". This is also true especially for women, as for a given height, they tend to have longer femurs than men.
On a final point I have no problem paying extra for more legroom, but this really is rarely available on its own and often is too expensive due to all the flashy unnecessary extras that come with it. Just try doing it, and you'll soon find how difficult it is.