Yeah a walk is not going to do much for your fitness if you're already relatively fit. I presently only walk as part of my work commute but when I have a lot of shit on my mind/heart I like to go for a longer walk. I've been toying with the idea of going to a different train stop that's further away so that I walk more in the mornings. I'm not expecting it to do shit for my fitness, but it's a nice way to start the day and get some outside time. I'm pretty fit/active so if I was looking to do something "for my fitness" while outside I would sprint and/or do calisthenics, etc.
So, if there's something else you think is going to be more beneficial then just do that. If you're fit enough to, then by all means. I'm looking at the morning walks as "me" time, not fitness improvement time. However, I'm not saying walking is detrimental to fitness (on the contrary) but it's not going to improve your lifts or your mile time, either.
I used to seriously post here, now I prefer to troll.