I can't imagine 6'1 and thinking 220 is "too thin" that's 4 inches and a 100 pounds over me... Oh well, if it looks right and you feel okay I guess that's all that counts.
As much as I support the BMI model and what it's trying to do, there's also a huge amount of basic logic and predisposed body type configurations it simply cannot compute.
Not everyone is built the same. Even two people of the same height can have wildly different builds. It's the classic ectomorph vs. mesomorph argument. Some people just have a very wide, over built frame and a huge amount of natural muscle mass. Trying to diet against that just leaves them miserable. And trying to force them into a mold and tell them they are overweight is doing noone any favors.
With the ecotomorph they are never going to look like Arnold Schwarznegger. It's just not in the cards for them. Trying to eat 5000 calories a day and 400 grams of protein is just not doing your body any favors. You weren't built to look that way.
Now where it gets fuzzy is with those body types there are basic assumptions we can largely make. Simply, thinner people with lower calorie diets *are* going to live longer. There are legitimate health benefits to having that build and trying to maintain that.
What the BMI scale tries to do is address everyone else that *isn't* a genetic freak and take a cut down the middle that includes everyone else. These are the people with beer guts, love handles, flabby arms, ect. Basically 50% or more of the adult population. BMI is a very simple guideline that says "Hey, here's your height and a range of weights that you should try and hit". Get above certain ranges and you are putting yourself at risk of heart disease and some other bad stuff. Try and stay below that.
I guess the really important takeaway that no one really wants to address is that we all have very different body types and each of those comes with a pro and con. Try and live within that body type and don't take it to the extreme (which is what the BMI range is there for) and then just do everything else you have control over - diet, lifestyle choices, ect and enjoy your life.
Get regular wellness exams from your primary care doc, have your vitals checked, labs drawn every couple years and respond as needed.