" You are buying into an ecosystem."
WHY DO YOU HATE CAPITALISM AND INNOVATION, YOU GODLESS COMMIE!!!???!!!
You are 100% right.
As it stands right now I have a grand total of ONE cordless tool... A Hitachi 18 volt cordless drill.
All of my other tools are either person powered or cord powered.
To be 100% honest, there really aren't that many situations in which a cordless tool is going to be very advantageous to me. A LITTLE more convenient, maybe, but a true advantage? No.
My Hitachi drill is a different story, though. A drill/screwdriver is used so much that going cordless really makes sense.
I bought the same drill that Castle Key bought (he bought his, I really liked it and my corded drill had crapped out, so I bought one a few months later).
That has come in handy a number of times when I've been helping him with projects, most recently earlier this year when I helped him build his greenhouse and the base on which it sits. We drove a TON of screws to tie everything together.
Having two drills and not having to worry about dragging cords from the garage while being able to charge batteries that could be used in either drill was a real advantage, especially when we had one drill set up to drill pilot holes and the other set up to drive the fasteners.
We could have done that with two totally different drills/battery systems, but it was marginally easier given the compatibility.